[SDK-4142] Add support for /oauth/par

[stevehobbsdev]

Changes

This PR implements two new auth API methods:

• pushed_authorization_request: calls the /oauth/par endpoint with all the parameters that would normally be sent to /authorize, and returns the payload including request_uri
• par_authorization_url: accepts request_uri and builds a URL that includes it along with client_id

Note

Something I would like some feedback on: the SDK already exposes authorization_url (source) that builds a URL for /authorize with all the params. However, I decided not to support PAR here for two reasons:

• It currently takes a required parameter redirect_url that is not required for the PAR request
• It currently takes a set of additional parameters to include in the request, all of which will be ignored by the server when sending a request_uri

It made sense to build a new method. However, also looking for feedback on the name par_authorization_url.

Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. If this library has unit and/or integration testing, tests should be added for new functionality and existing tests should complete without errors.

• This change adds unit test coverage
• This change adds integration test coverage
• This change has been tested on the latest version of Ruby

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
• Rubocop passes on all added/modified files
• All active GitHub checks have passed

[stevehobbsdev]

Until now the SDK didn't have a way to send a POST request with application/x-www-form-urlencoded, it always assumed JSON. To support this, I added a new method type here (which ultimately ends up as a POST, similar to how :post_file is used).

The alternative was to add an option to the method that signals the developer wants to use form data, but there was no way to do this without introducing a potential breaking change.