Update base64 crate and use it in place of base64-url

[paolobarbolini]

Updates the base64 crate to 0.21 and uses it everywhere for base64 url-safe encoding and decoding.

Let me know if you like the small module I created to wrap the base64 API with something easier to use or if you'd prefer calling base64 directly

[paolobarbolini]

Sorry I pushed again as i forgot to run clippy

[caspervonb]

Thank you for the effort.

This is more code rather than less, so am not inclined to merge as-is.

Might merge if you remove the base64 helper module, as most of those functions have helpers elsewhere (e.g encode_object_name is just calling encode with URL_SAFE config already.

[paolobarbolini]

Finally got the various different encodings right. I'll remove the base64.rs helper module next and squash everything

[paolobarbolini]

This should now be ready to be merged

[caspervonb]

lgtm, thank you @paolobarbolini

[Jarema]

LGTM