feat(flow): Poc dataflow demo #15571

Job	Run time
Check (windows-latest)	7m 40s
Clippy	3m 15s
Build GreptimeDB binaries (ubuntu-20.04)	6m 52s
Check (ubuntu-20.04)	2m 55s
Check typos and docs	29s
Rustfmt	45s
Toml Check	50s
coverage	0s
Sqlness Test with Kafka Wal (ubuntu-20.04)	3m 14s
Fuzz Test (fuzz_create_table)	7m 2s
Sqlness Test (ubuntu-20.04)	2m 29s
Fuzz Test (fuzz_alter_table)	6m 5s
Fuzz Test (fuzz_create_database)	5m 54s
Fuzz Test (fuzz_create_logical_table)	6m 19s
Fuzz Test (fuzz_alter_logical_table)	6m 4s
	59m 53s

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