prevent constant diff even after a successful apply of resource_tfe_registry_module resource

[Uk1288]

Description

This PR prevents constant diff even after a successful apply of resource_tfe_registry_module resource. It also fixes the following cases:

• when tags is set to true and branch is specified, the API ignores tags value and uses the specified branch. This leads to a constant diff attempt. Solution added is to match the API by verifying that either branch or tags is set but not both
• previously, the tags value was never sent during the Create request, this PR ensures that the specified tags value is always sent in the request
• test_config was only updated into state when the test config response is non-empty leading to never unsetting the value in state. Added fix to always update the test_config state to reflect api response.
• adds some tests to catch previously failing cases
• fix panic that occurs while logging errors during registry module create

Remember to:

• Update the Change Log

Testing plan

1. Some configs like below resulted in constant diff even after a successful apply

resource "tfe_registry_module" "test-without-test-config-block" {
 vcs_repo {
    display_identifier = "Uk1288/terraform-aws-simple-s3-cdn"
    identifier         = "Uk1288/terraform-aws-simple-s3-cdn"
    oauth_token_id     = "ot-123"
    branch             = "main"
    tags             = false
    # branch             = ""
    # tags               = true
  }
}

resource "tfe_registry_module" "bare-module" {
  vcs_repo {
    oauth_token_id     = "ot-123"
    display_identifier = "Uk1288/terraform-google-cloud-dns"
    identifier         = "Uk1288/terraform-google-cloud-dns"
  }
}

resource "tfe_registry_module" "test-with-tags-and-branch-disabled" {
 vcs_repo {
    display_identifier = "Uk1288/terraform-aws-simple-s3-cdn"
    identifier         = "Uk1288/terraform-aws-simple-s3-cdn"
    oauth_token_id     = "ot-123"
    tags             = false
    branch         = ""
  }
}

1. Applying tfe_registry_module config combo should no longer result in constant diff,

$ TESTARGS="-run TestAccTFERegistryModule" make testacc

=== RUN   TestAccTFERegistryModule_vcs
--- PASS: TestAccTFERegistryModule_vcs (7.69s)
=== RUN   TestAccTFERegistryModule_GitHubApp
--- PASS: TestAccTFERegistryModule_GitHubApp (4.32s)
=== RUN   TestAccTFERegistryModule_emptyVCSRepo
--- PASS: TestAccTFERegistryModule_emptyVCSRepo (0.19s)
=== RUN   TestAccTFERegistryModule_nonVCSPrivateRegistryModuleWithoutRegistryName
--- PASS: TestAccTFERegistryModule_nonVCSPrivateRegistryModuleWithoutRegistryName (4.29s)
=== RUN   TestAccTFERegistryModule_nonVCSPrivateRegistryModuleWithRegistryName
--- PASS: TestAccTFERegistryModule_nonVCSPrivateRegistryModuleWithRegistryName (4.11s)
=== RUN   TestAccTFERegistryModule_publicRegistryModule
--- PASS: TestAccTFERegistryModule_publicRegistryModule (4.14s)
=== RUN   TestAccTFERegistryModule_vcsRepoWithTagField
--- PASS: TestAccTFERegistryModule_vcsRepoWithTagField (6.30s)
=== RUN   TestAccTFERegistryModuleImport_vcsPrivateRMDeprecatedFormat
--- PASS: TestAccTFERegistryModuleImport_vcsPrivateRMDeprecatedFormat (7.75s)
=== RUN   TestAccTFERegistryModuleImport_vcsPrivateRMRecommendedFormat
--- PASS: TestAccTFERegistryModuleImport_vcsPrivateRMRecommendedFormat (6.87s)
=== RUN   TestAccTFERegistryModuleImport_vcsPublishingMechanismBranchToTagsToBranch
--- PASS: TestAccTFERegistryModuleImport_vcsPublishingMechanismBranchToTagsToBranch (16.40s)
=== RUN   TestAccTFERegistryModuleImport_vcsPublishingMechanismBranchToTagsToBranchWithTests
--- PASS: TestAccTFERegistryModuleImport_vcsPublishingMechanismBranchToTagsToBranchWithTests (11.21s)
=== RUN   TestAccTFERegistryModuleImport_vcsPublishingMechanismTagsToBranchToTags
--- PASS: TestAccTFERegistryModuleImport_vcsPublishingMechanismTagsToBranchToTags (13.98s)
=== RUN   TestAccTFERegistryModule_invalidTestConfigOnCreate
--- PASS: TestAccTFERegistryModule_invalidTestConfigOnCreate (3.28s)
=== RUN   TestAccTFERegistryModule_invalidTestConfigOnUpdate
--- PASS: TestAccTFERegistryModule_invalidTestConfigOnUpdate (7.02s)
=== RUN   TestAccTFERegistryModule_branchAndInvalidTagsOnCreate
--- PASS: TestAccTFERegistryModule_branchAndInvalidTagsOnCreate (2.94s)
=== RUN   TestAccTFERegistryModule_branchAndTagsEnabledOnCreate
--- PASS: TestAccTFERegistryModule_branchAndTagsEnabledOnCreate (2.76s)
=== RUN   TestAccTFERegistryModule_branchAndTagsDisabledOnCreate
--- PASS: TestAccTFERegistryModule_branchAndTagsDisabledOnCreate (2.81s)
=== RUN   TestAccTFERegistryModule_branchAndTagsEnabledOnUpdate
--- PASS: TestAccTFERegistryModule_branchAndTagsEnabledOnUpdate (7.02s)
=== RUN   TestAccTFERegistryModule_branchAndTagsDisabledOnUpdate
--- PASS: TestAccTFERegistryModule_branchAndTagsDisabledOnUpdate (7.31s)
=== RUN   TestAccTFERegistryModuleImport_nonVCSPrivateRM
--- PASS: TestAccTFERegistryModuleImport_nonVCSPrivateRM (4.23s)
=== RUN   TestAccTFERegistryModuleImport_publicRM
--- PASS: TestAccTFERegistryModuleImport_publicRM (4.33s)
=== RUN   TestAccTFERegistryModule_invalidWithBothVCSRepoAndModuleProvider
--- PASS: TestAccTFERegistryModule_invalidWithBothVCSRepoAndModuleProvider (0.15s)
=== RUN   TestAccTFERegistryModule_invalidRegistryName
--- PASS: TestAccTFERegistryModule_invalidRegistryName (0.32s)
=== RUN   TestAccTFERegistryModule_invalidWithModuleProviderAndNoName
--- PASS: TestAccTFERegistryModule_invalidWithModuleProviderAndNoName (0.13s)
=== RUN   TestAccTFERegistryModule_invalidWithModuleProviderAndNoOrganization
--- PASS: TestAccTFERegistryModule_invalidWithModuleProviderAndNoOrganization (0.13s)
=== RUN   TestAccTFERegistryModule_invalidWithNamespaceAndNoRegistryName
--- PASS: TestAccTFERegistryModule_invalidWithNamespaceAndNoRegistryName (0.12s)
=== RUN   TestAccTFERegistryModule_invalidWithRegistryNameAndNoModuleProvider
--- PASS: TestAccTFERegistryModule_invalidWithRegistryNameAndNoModuleProvider (0.12s)

unrelated failure for nocode

=== RUN TestAccTFERegistryModule_noCodeModule
resource_tfe_registry_module_test.go:343: Step 1/1 error: Error running apply: exit status 1

    Error: Error creating registry module vpc: resource not found
    
      with tfe_registry_module.foobar,
      on terraform_plugin_test.tf line 8, in resource "tfe_registry_module" "foobar":
       8: resource "tfe_registry_module" "foobar" {

--- FAIL: TestAccTFERegistryModule_noCodeModule (2.23s)

[brandonc]

It works! Under what conditions do our normal test cases catch this behavior?