Remove internal type OAuth::Params

[AnandRaj2224]

The internal type OAuth::Params was redundant and used only by OAuth::Signature.
This refactor replaces it with URI::Params plus an RFC3986-compatible normalization method.
All stdlib specs pass (0 failures, 0 errors).
Fixes #16317

[AnandRaj2224]

Updated according to review:

1.Removed OAuth::Params and replaced with URI::Params
2.Added add_query_params helper
3.Used URI.encode_www_form(..., space_to_plus: false) for RFC3986 compliance
4.Preserved legacy parameter order for clarity
5.Refactored normalization with String.build

All std specs are passing.
Please take a look when you can — thank you!

[straight-shoota]

I have a few nitpicks, mostly about unnecessary stylistic changes, but also found semantic problems.

[AnandRaj2224]

Hi @straight-shoota,
Just following up to see if you’ve had a chance to review this again.
I’ve implemented the RFC 5849–compliant change (encoding before sorting) and added the inline notes as suggested.
Everything’s passing and ready for another look when you have time — thanks again for your feedback earlier!

[ysbaddaden]

Just one last tidbit. Thanks for your patience with all these changes 🙇

[AnandRaj2224]

Thanks @ysbaddaden
I applied all the suggested changes:

• Replaced the manual flattening/String.build loop with 'params.map', using the encoded 'key' and 'value'.
• Removed 'add_query_params' entirely and inlined the two 'URI::Params.parse' calls.

The code is now much cleaner and matches the recommended approach.
Let me know if you'd like anything else adjusted!

[ysbaddaden]

Needs a crystal tool format, and that's it.