[Variant] Add variant_get and Shredded VariantArray

[alamb]

Which issue does this PR close?

• Part of [EPIC] [Parquet] Implement Variant type support in Parquet #6736
• Closes [Variant] Support variant_get kernel for shredded variants #7941
• Closes [Variant] WIP Tests for variant_get of shredded variants #7965

Rationale for this change

This is has a proposal for how to structure shredded VariantArrays and the variant_get kernel

If people like the basic idea I will file some more tickets to track additional follow on work

It is based on ideas ideas from @carpecodeum in #7946 and @scovich in #7915

I basically took the tests from #7965 and the conversation with @scovich recorded from #7941 (comment) and I bashed out how this might look

What changes are included in this PR?

1. Update VariantArray to represent shredding
2. Add code to variant_get to support extracting paths as both variants and typed fields
3. A pattern that I think can represent shredding and extraction
4. Tests for same

Note there are many things that are NOT in this PR that I envision doing as follow on PRs:

1. Support and implementing Paths
2. Support for shredded objects
3. Support shredded lists
4. Support nested objects / lists
5. Full casting support
6. Support for other output types: StringArray, StringViewArray, etc
7. Many performance improvements

Are these changes tested?

Yes

Are there any user-facing changes?

New feature