feat: support casting FixedSizeList with new child type

[wjones127]

Which issue does this PR close?

Closes #4426.

Rationale for this change

Makes it possible to cast between FixedSizeList arrays with different child types. We use this to be able to cast f32 vectors into f16 vectors to store them at a smaller size.

What changes are included in this PR?

Dispatch to child cast_with_options when appropriate to allow FSL -> FSL/List/LargeList with differing child types.

Are there any user-facing changes?

Yes, though I don't think we document all possible cast option at the moment.

[alamb]

The code and tests look good to me. Thank you @wjones127

While reviewing the code, I noticed the casts were in only in the FixedSizedList --> List/LargeList direction. Would it make sense to do the reverse too (List/LargeLIst --> FixedSizedLIst)

Specifically I was imagining preserving the arrays during round trip might be important (and easy to test): FixedSizeList --> List --> FixedSizedList

🤔

[alamb]

Thanks again @wjones127 and @tustvold

[wjones127]

@alamb Sorry for not replying earlier. I did the casts for the other direction earlier in #5081. I didn't think to add a roundtrip test specifically, but I think the individual tests are specific enough to imply they will roundtrip.

[alamb]

@alamb Sorry for not replying earlier. I did the casts for the other direction earlier in #5081. I didn't think to add a roundtrip test specifically, but I think the individual tests are specific enough to imply they will roundtrip.

No worries -- makes sense to me.