Implement show flint index statement

[seankao-az]

Description

This PR implements the SHOW FLINT INDEX IN catalog[.database] statement, with the following output columns:

• flint_index_name: the full OpenSearch index name
• kind: type of the index (skipping / covering / mv)
• database: database name for the index
• table: table name for skipping and covering index
• index_name: user defined name for covering index and materialized view
• auto_refresh: auto refresh option of the index (true / false)
• status: status of the index. It's fetched from Flint metadata log.

Example:

spark-sql> SHOW FLINT INDEXES IN mys3;
flint_mys3_default_http_count_view	mv	default	NULL	http_count_view	false	active
flint_mys3_default_http_logs_skipping_index	skipping	default	http_logs	NULL	false	active
flint_mys3_default_http_logs_status_clientip_and_request_index	covering	default	http_logs	status_clientip_and_request	false	active

Issues Resolved

• [FEATURE] Show Flint indexes support #265

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[dai-chen]

Thanks for the changes!