Support Python 3.10+ changes to the AST

[Technologicat]

There have been some recent changes to the Python AST:

• Python 3.10: match/case (pattern matching, now a native Python feature)
• Python 3.11: try/except* (exception groups)
• Python 3.12: type statement (type alias)

Full details in official docs.

Question is, what do we need to change in unpythonic to support these? At least:

• DONE in 58388fc: lazify and autocurry should not recurse into ast.TypeAlias, because lazifying or autocurrying a type declaration makes no sense.
• DONE in 040e333: Anything that touches on exception handling in the macro layer needs to detect TryStar as well as Try.
  • Not much detects Try; just autoreturn and scopeanalyzer.
• DONE in faab516: Anything that detects binding forms needs to detect captures in match/case.
  • It seems unpythonic/syntax/scopeanalyzer.py is the only such part. But this is used in the let constructs (including do) as well as in lazify, so fixing that should be enough.
  • Bindings from the type statement are handled automatically by the old machinery, because they are names in Store context.

Anything else I'm missing?

[Technologicat]

Since the parts I'm aware of are now done, but there may still be something I've missed, I'm keeping this ticket open, but moving it to the 0.15.4 milestone.