fix(rpc): taosd stuck when exiting the process

fix: memory error

enh: stream supports filter

fix: fix hb crash issue

enh: refactor unit test of parser and planner

test: case for math functions 

fix: subscrption api

feat: bsma aggr data optimization

fix(query): alter the type of result of the length function.

refactor(index): refactor index code

test: add test case for checking network by taos

test : add char_length case

refactor(query): remove redundant attributes in some structs.

feat(query): add spread function

feat: migrate tsdb read interface to vnode