feat: impl show index and show columns #14548

Job	Run time
Build GreptimeDB binaries (ubuntu-20.04)	4m 0s
Check (windows-latest)	6m 28s
Rustfmt	23s
Check (ubuntu-20.04)	1m 25s
Clippy	2m 9s
Toml Check	25s
coverage	10m 54s
Spell Check with Typos	20s
Compatibility Test	29s
Sqlness Test with Kafka Wal (ubuntu-20.04)	3m 25s
Fuzz Test (fuzz_create_table)	4m 53s
Sqlness Test (ubuntu-20.04)	5m 18s
Fuzz Test (fuzz_alter_table)	5m 41s
	45m 50s

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