resource/aws_rds_cluster: Add engine_mode argument

[bflad]

Closes #5503

Changes proposed in this pull request:

• Add engine_mode argument to aws_rds_cluster resource
• Remove Default: false from storage_encrypted attribute as serverless engine_mode requires it to be enabled
• Allow storage_encrypted attribute to ignore differences with serverless engine_mode configurations that omit the argument

Output from acceptance testing:

=== RUN   TestAccAWSRDSCluster_missingUserNameCausesError
--- PASS: TestAccAWSRDSCluster_missingUserNameCausesError (3.02s)
=== RUN   TestAccAWSRDSCluster_basic
--- PASS: TestAccAWSRDSCluster_basic (97.58s)
=== RUN   TestAccAWSRDSCluster_encrypted
--- PASS: TestAccAWSRDSCluster_encrypted (97.53s)
=== RUN   TestAccAWSRDSCluster_EngineVersion
--- PASS: TestAccAWSRDSCluster_EngineVersion (98.40s)
=== RUN   TestAccAWSRDSCluster_backupsUpdate
--- PASS: TestAccAWSRDSCluster_backupsUpdate (100.42s)
=== RUN   TestAccAWSRDSCluster_updateCloudwatchLogsExports
--- PASS: TestAccAWSRDSCluster_updateCloudwatchLogsExports (100.46s)
=== RUN   TestAccAWSRDSCluster_updateIamRoles
--- PASS: TestAccAWSRDSCluster_updateIamRoles (109.66s)
=== RUN   TestAccAWSRDSCluster_kmsKey
--- PASS: TestAccAWSRDSCluster_kmsKey (117.40s)
=== RUN   TestAccAWSRDSCluster_generatedName
--- PASS: TestAccAWSRDSCluster_generatedName (120.92s)
=== RUN   TestAccAWSRDSCluster_namePrefix
--- PASS: TestAccAWSRDSCluster_namePrefix (121.47s)
=== RUN   TestAccAWSRDSCluster_importBasic
--- PASS: TestAccAWSRDSCluster_importBasic (127.24s)
=== RUN   TestAccAWSRDSCluster_iamAuth
--- PASS: TestAccAWSRDSCluster_iamAuth (127.44s)
=== RUN   TestAccAWSRDSCluster_BacktrackWindow
--- PASS: TestAccAWSRDSCluster_BacktrackWindow (130.05s)
=== RUN   TestAccAWSRDSCluster_updateTags
--- PASS: TestAccAWSRDSCluster_updateTags (141.08s)
=== RUN   TestAccAWSRDSCluster_takeFinalSnapshot
--- PASS: TestAccAWSRDSCluster_takeFinalSnapshot (158.51s)
=== RUN   TestAccAWSRDSCluster_Port
--- PASS: TestAccAWSRDSCluster_Port (182.46s)
=== RUN   TestAccAWSRDSCluster_EngineMode
--- PASS: TestAccAWSRDSCluster_EngineMode (264.97s)
=== RUN   TestAccAWSRDSCluster_SnapshotIdentifier
--- PASS: TestAccAWSRDSCluster_SnapshotIdentifier (303.42s)
=== RUN   TestAccAWSRDSCluster_SnapshotIdentifier_Tags
--- PASS: TestAccAWSRDSCluster_SnapshotIdentifier_Tags (293.30s)
=== RUN   TestAccAWSRDSCluster_SnapshotIdentifier_VpcSecurityGroupIds
--- PASS: TestAccAWSRDSCluster_SnapshotIdentifier_VpcSecurityGroupIds (294.25s)
=== RUN   TestAccAWSRDSCluster_SnapshotIdentifier_VpcSecurityGroupIds_Tags
--- PASS: TestAccAWSRDSCluster_SnapshotIdentifier_VpcSecurityGroupIds_Tags (334.56s)
=== RUN   TestAccAWSRDSCluster_SnapshotIdentifier_EngineMode
--- PASS: TestAccAWSRDSCluster_SnapshotIdentifier_EngineMode (363.30s)
=== RUN   TestAccAWSRDSCluster_s3Restore
--- PASS: TestAccAWSRDSCluster_s3Restore (1494.30s)
=== RUN   TestAccAWSRDSCluster_EncryptedCrossRegionReplication
--- PASS: TestAccAWSRDSCluster_EncryptedCrossRegionReplication (1659.33s)

[tombuildsstuff]

LGTM 👍

[bflad]

This has been released in version 1.32.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!