Add endpoint_management attribute

[mbtiii]

What does this PR do?

• Added support for the endpoint_management attribute on MWAA environments.
  • This allows you to create MWAA environments inside VPCs that are owned by other accounts, as long as you manually create the VPC endpoints required by Airflow.
• Bumped up the AWS provider requirements to the earliest version that supports the new attribute

Motivation

We wanted to migrate our Airflow clusters, which were created with this module, to a shared VPC.

Relevant issue: #58

More

• Yes, I have tested the PR using my local account setup (Provide any test evidence report under Additional Notes)
• Yes, I ran pre-commit run -a with this PR
  • It failed, but for the same reasons that already existed before this PR (i.e., problems with the examples/basic code)

For Moderators

• E2E Test successfully complete before merge?

Additional Notes

• When deploying an environment with endpoint_management="CUSTOMER", the cluster creation will hang until you've created the endpoint yourself. If it times out, you may need to terraform untaint the cluster after it's finished being created. This is a deficiency in the resource itself.
• Creating the endpoint via Terraform is not easy since the AWS provider does not have a data element for aws_mwaa_environment, and the attributes are not available via the resource until after it has been created.

Evidence of Deployment

Note that many values have been redacted for our own security:

> tf state show module.mwaa.aws_mwaa_environment.mwaa
# module.mwaa.aws_mwaa_environment.mwaa:
resource "aws_mwaa_environment" "mwaa" {
    airflow_configuration_options   = (sensitive value)
    airflow_version                 = "2.7.2"
    arn                             = "arn:aws:airflow:XXXXXX:XXXXXXXXXXXX:environment/XXXXXX"
    created_at                      = "2024-07-10 17:54:17 +0000 UTC"
    dag_s3_path                     = "dags/"
    endpoint_management             = "CUSTOMER" <------ This is the attribute I added
    environment_class               = "mw1.small"
    execution_role_arn              = "arn:aws:iam::XXXXXXXXXXXX:role/XXXXXX"
    id                              = "XXXXXX"
    last_updated                    = [
        {
            created_at = "2024-07-10 17:54:17 +0000 UTC"
            error      = []
            status     = "SUCCESS"
        },
    ]
    max_workers                     = 3
    min_workers                     = 3
    name                            = "XXXXXX"
    plugins_s3_object_version       = "XXXXXX"
    plugins_s3_path                 = "plugins/plugins.zip"
    requirements_s3_object_version  = "XXXXXX"
    requirements_s3_path            = "requirements/requirements.txt"
    schedulers                      = 2
    service_role_arn                = "arn:aws:iam::XXXXXXXXXXXX:role/aws-service-role/airflow.amazonaws.com/AWSServiceRoleForAmazonMWAA"
    source_bucket_arn               = "arn:aws:s3:::XXXXXX"
    status                          = "AVAILABLE"
    tags                            = {}
    tags_all                        = {
        ...
    }
    webserver_access_mode           = "PUBLIC_ONLY"
    webserver_url                   = "XXXXXX.XXXXXX.XXXXXX.airflow.amazonaws.com"
    weekly_maintenance_window_start = "MON:07:30"

    logging_configuration {
        ...
    }

    network_configuration {
        security_group_ids = [
            "sg-XXXXXX",
        ]
        subnet_ids         = [
            "subnet-XXXXXX", <------ These subnets do not belong to the account
            "subnet-XXXXXX",
        ]
    }
}