Support Decimal32/64 types

[AdamGS]

Which issue does this PR close?

Closes #17489.

Rationale for this change

Since Arrow 56 and #16690, support has been added to the two smaller decimal variants. This PR tries to bring support to them on-par with the support for the bigger types.

I've run into this issue when upgrading Vortex to use the upcoming release (50), one of our benchmarks fails with:

Error during planning: Execution error: Function 'sum' user-defined coercion failed with "Execution error: Sum not supported for Decimal32(7, 2)" No function matches the given name and argument types 'sum(Decimal32(7, 2))'. You might need to add explicit type casts.
	Candidate functions:
	sum(UserDefined)

What changes are included in this PR?

Adding support for handling decimal32/64 wherever other decimal types are handled. I've tried to use multiple search methods to find places where they matter, but there might be some matches/if conditions that make them hard to find.

I've also implemented support for AVG, SUM, FIRST_VALUE/LAST_VALUE and MIN/MAX. but I stopped pushing MEDIAN and MIN_MAX as I'm not sure if its desirable (at all) or as part of this PR. Seems like implementing these aggregations is required to get the test suite to ✅, so I'm working on adding everything.

Are these changes tested?

The testing strategy to some of these parts is unclear to me, both around SQL but also for aggregate functions like SUM and AVG.

Are there any user-facing changes?

Code that used to fail while reading some decimals should now work.