[Analyzer] No way to analyze scripts

It seems that ZetaSQL supports whole-script parsing (`Parser::ParseScript`), which, significant for my purpose, allows analysis of scripts with toplevel `DECLARE` statements, as is also possible within BigQuery.
But the Analyzer API (in C++ as well as Java) does not provide an interface to this functionality, so I'm stuck with having to wrap my scripts with a superfluous `BEGIN`/`END` block.
It'd be nice if this where a supported feature.