Adds support for /branding endpoints

[connorconway]

Changes

Added support for the /branding endpoint (GET/PATCH)
Added support for the /branding/templates/universal-login endpoint (GET/DELETE/PUT)

References

Get Branding Docs
Patch Branding Docs
Get Universal Login Docs
Delete Universal Login Docs
Put Universal Login Docs

Testing

I added a reference to the assemblies within our deploy tool and tested retrieving and updating the branding, setting the universal login template, retrieving the universal login template, and deleting the universal login template.

• This change adds unit test coverage

• This change adds integration test coverage.
  -- Needed but I'm unable to write these

• This change has been tested on the latest version of the platform/language

Checklist

• I have read the Auth0 general contribution guidelines

• I have read the Auth0 Code of Conduct

• All existing and new tests complete without errors.
  -- I'm unable to run the integration tests to check if they pass, so there's a possibility of failure there. Unit tests pass.

[frederikprijck]

Thanks for the PR @connorconway . I added some integration tests and updated the docs.
There was also an issue with the UniversalLoginTemplateUpdateRequest object. It doesnt support the Body property, the payload needs to either be a string or an object with a Template property. (The docs aren't very clear on that).