Updates to MWAA verify environment script

[CihanBosnali]

Issue #, if available: Closes #165 #171 #179 #185 #203 #204 #205 #209

Description of changes:

1. Check for two IAM permissions that are not currently being checked although used by the MWAA execution role (allow logs:GetQueryResults and allow logs:GetLogRecord).
2. Check IAM permissions necessary to access REST API.
3. Check if Airflow REST API invocation to GET /health endpoint succeeds, output the API response that includes status and heartbeat of Airflow components.
4. Check SQS celery executor queue health using CloudWatch metrics.
5. Divide output as full report and key findings, write them to files.
6. Suggest to upgrade to a larger environment class based on CloudWatch metrics and # of dags.
7. Check for cache folders in the S3 dags folder that are not being ignored by .airflowignore. (.ipynb_checkpoints, .git, __pycache__)
8. Upload and run a simple DAG.
9. Check secrets manager configuration.
10. Check airflow configuration options for celery.worker_concurrency and core.lazy_load_plugins.
11. _check_access_blocked no longer breaks script when user does not have permission to check access.
12. region argument to script is made a required argument.
13. VPC endpoint identification no longer fails if endpoint is connected to more subnets than the MWAA environment.
14. Profile name validation no longer fails with hyphens and underscores, no longer passes incorrectly with empty string.

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[ankon]

This breaks the script: import json is missing.

@CihanBosnali PTAL at #247, which contains a fix for this problem.