refactor: free rpcCont on error occured

fix: memory error

fix: some prblems of parser and planner

fix(stream): avoid check data update for tmq

refactor: adjust error codes

fix(query): set the correct schema version for rows in buffer.

fix(query): specify the primary timestamp column in ssdatablock

test:open all cases of stb in tmq

docs: add missing files in docs-examples

fix: vnode snapshot

refactor: adjust error codes

enh: delete redundancy code

docs: copy docs-examples from 2.6 to 3.0

fix(query): specify the primary timestamp column in ssdatablock when update the time range of ssdatablock.

test: case for alter stable