RNTuple support

[ariostas]

I'm opening this issue to have a central place to check the status of RNTuple support in Uproot. I'll add and check off items to keep it updated.

RNTuple Reading

As far as I can tell, 100% of the spec is already supported. I'll update this if I find out otherwise.

• Tuples should be read as tuples instead of records
• The arrays method needs to have more functionality to be on par with TTrees
• Refactoring to improve readability and performance

RNTuple Writing

• Basic metadata (field records, column records, etc...) feat: basic RNTuple writing #1356
• Flat arrays of native types (except booleans) feat: basic RNTuple writing #1356
• Boolean arrays feat: all essential RNTuple writing functionality #1395
• Jagged arrays and string arrays feat: all essential RNTuple writing functionality #1395
• Structs and arrays of structs feat: all essential RNTuple writing functionality #1395
• Optional and union types feat: all essential RNTuple writing functionality #1395
• Compression support
• Better page splitting

Dask support

• Reading with Dask
• Writing with Dask

Other likely additions

• Schema evolution

Unlikely additions

• Alias columns
• Projected fields
• Alternative representations