Add migrate-db command and support airflow downgrades

[michaelfu1029]

Issue #, if available:

Description of changes:
Added a new command migrate-db for a special container that will run the same airflow db init/upgrade logic but will also check for an environment variable MWAA__CORE__TARGET_VERSION to downgrade. Existing inplace upgrade will not be changed for now.

The migrate_with_downgrade.py file is a copy or migrate.py but with an additional downgrade check

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[sudiptoghosh01]

Can you please include the corresponding unit test for your code changes. I see the quality checks are failing for this change.

[michaelfu1029]

Unit tests are added, is only failing because did not add test for

if command == "migrate-db":
        await airflow_db_migrate(environ)
        print("Finished running db validations")
        return

but there is already a unit test for airflow_db_migrate() so I don't believe this is necessary. I believe we also don't have coverage tests for other commands

[sudiptoghosh01]

Unit tests are added, is only failing because did not add test for

if command == "migrate-db":
        await airflow_db_migrate(environ)
        print("Finished running db validations")
        return

but there is already a unit test for airflow_db_migrate() so I don't believe this is necessary. I believe we also don't have coverage tests for other commands

I believe you should cover this branch as well. Similar to what we have for other commands, please refer to this code pointer.

Resolved