PostgreSQL compatibility: `extract(second ...)` should preserve fractional seconds

[Dandandan]

Split out from #22247.

Mismatch

extract(second ...) should preserve fractional seconds.

SELECT extract(second from timestamp '2020-01-01 00:00:12.345678');

PostgreSQL:

12.345678

DataFusion:

12

Expected behavior

For PostgreSQL-compatible SQL semantics, DataFusion should either match PostgreSQL's result or raise the same class of domain/semantic error.