feat: block-wise sma integrate

enh(query): set the parameters for system database to be NULL

fix(query): translate var type from value node to SVariant should include var header

ehn(query): set the parameters for system database to be NULL by default when responsing "show databases" command.

fix(query): fix bug in calculating the aggregate function

fix(query): fix bug in calculating the aggregate function with constant numeric value as input parameter.

refactor: vnode

fix(build): use static taos lib.

enh: add tag index filter impl

fix(query): enable to employ the scalar function as the parameter of  the aggregate function.

refactor: vnode