all: Add ephemeral resource schema and lifecycle tests

[austinvalle]

This PR introduces some smoke tests for ephemeral resources released in terraform-plugin-framework v1.13.0, which are available in Terraform v1.10.0-beta.

There is one known bug in Terraform core where ephemeral resources are invoked with unknown values, which should not happen (similar to data sources, which are skipped until all config values are known). I wrote a negative test here for us to update once the next Terraform core beta releases with the fix.

^^ This has been adjusted to a normal positive test in 046f43c now that we're running 1.10.0-rc1 ⚡

TODOs left

This PR relies on in-progress work on a test echo provider from terraform-plugin-testing, so this PR won't be merged until that work is merged/released.

• Update terraform-plugin-testing dependency in go.mod after tfversion: Add SkipIfNotAlpha version check terraform-plugin-testing#388 and echoprovider: Add a new test-only v6 provider that echoes ephemeral provider data terraform-plugin-testing#389 are merged/released

[austinvalle]

Heh, the deferred action tests are failing because we made the assumption that we'd only ever run tests on pre-releases that were alphas. We should probably create a more specific version check for usage here.

func TestDeferredActionResource_ProviderDeferral(t *testing.T) {
	resource.UnitTest(t, resource.TestCase{
		TerraformVersionChecks: []tfversion.TerraformVersionCheck{
			tfversion.SkipBelow(tfversion.Version1_9_0),
			// Beta is also pre-release, but doesn't have experiments (deferred actions) enabled 
			tfversion.SkipIfNotPrerelease(),
		},

[austinvalle]

Heh, the deferred action tests are failing because we made the assumption that we'd only ever run tests on pre-releases that were alphas. We should probably create a more specific version check for usage here.

I opened hashicorp/terraform-plugin-testing#388 and merged it into the echoprovider branch that this PR is using. Both the echoprovider changes and the SkipIfNotAlpha changes should be released together 👍🏻