Add linode_database_mysql_v2 resource

[lgarber-akamai]

📝 Description

This pull request implements a new linode_database_mysql_v2 resource supporting the new Aiven-backed managed database clusters.

NOTE: This PR depends on and uses the design of #1680. Information on design decisions & caveats can be found in its description.

✔️ How to Test

The following test steps assume you have pulled down this PR locally and do not have your account configured for legacy DBaaS clusters.

Unit Testing

make unit-test

Integration Testing

make PKG_NAME=linode/databasemysqlv2 int-test
make PKG_NAME=linode/databaseaccesscontrols int-test

Manual Testing

1. In a terraform-provider-linode sandbox environment (e.g. dx-devenv), apply the following configuration:

 resource "linode_database_mysql_v2" "test" {
  region = "us-mia"
  label = "tf-test"
  type = "g6-nanode-1"
  engine_id = "mysql/8"

  allow_list = ["10.0.0.2/32", "10.0.0.3/32"]
  cluster_size = 3

  updates = {
    hour_of_day = 2
    day_of_week = 3
    frequency = "weekly"
    duration = 4
  }
}

NOTE: Database creations should take ~15 minutes.

2. Ensure the apply was successful and the database has been properly created in Cloud Manager.
3. Re-apply the configuration and ensure no changes are proposed.
4. Make arbitrary changes to the allow_list, cluster_size, type, and updates attributes.
5. Re-apply the configuration.
6. Ensure the apply was successful and the database has been properly updated in Cloud Manager.
7. Re-apply the configuration and ensure no changes are proposed.
8. Append the following to the end of your configuration to create a new database forked from the first database:

resource "linode_database_mysql_v2" "forked" {
  region = "us-mia"
  label = "tf-test-forked"
  type = "g6-nanode-1"
  engine_id = "mysql/8"

  source = linode_database_mysql_v2.test.id
}

9. Re-apply the configuration and validate that a new forked database has been created in Cloud Manager.
10. Re-apply the configuration and ensure no changes are proposed.
11. Destroy the configuration and ensure all databases are deleted as expected.

[jriddle-linode]

LGTM working locally with all tests!

[zliang-akamai]

Looks good and works well! There might be an intermittent failure, probably caused by the API/backend?
https://github.com/linode/terraform-provider-linode/actions/runs/12781955064/attempts/1

[lgarber-akamai]

Looks good and works well! There might be an intermittent failure, probably caused by the API/backend? https://github.com/linode/terraform-provider-linode/actions/runs/12781955064/attempts/1

Nice catch! This seems like another case of events being marked as finished before the resource exits the updating status. I think we can address this by polling for status after polling for the event to finish

[lgarber-akamai]

Integration test run: https://github.com/linode/terraform-provider-linode/actions/runs/12833090445