Add a `uuid` field type

[tezlm]

Is your feature request related to a problem? Please describe.
I'm using uuids as ids in my application, but tantivy doesn't support uuid fields!

Describe the solution you'd like
Add uuids as a field type.

[Optional] describe alternatives you've considered

• add_bytes: works, but is a bit unergonomic and might take up more space than if there was just a uuid(?) (unsure if this is true, haven't looked too deeply into tantivy's internals)
• two add_u64s: even more unergonomic

[PSeitz]

You can use text fields for uuids with the raw tokenizer

[tezlm]

wouldn't that take up more storage space? or is it neglectible?

[tezlm]

actually, i don't know what i was thinking. of course it would take up basically no space.

i still think having a uuid type could be nice for quality of life though