AUTH-6071 Add various features to Access OIDC SaaS applications

[ajholland]

Adds refresh token, custom claims, and pkce without client secret support to cloudflare-go

Description

docs: https://developers.cloudflare.com/api/operations/access-applications-list-access-applications

Has your change been tested?

unit tests

Screenshots (if appropriate):

Types of changes

What sort of change does your code introduce/modify?

• Bug fix (non-breaking change which fixes an issue)
• [ x] New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• This change is using publicly documented in cloudflare/api-schemas
  and relies on stable APIs.

[github-actions]

changelog detected ✅

[jacobbednarz]

confirming this is already in v2 as well - https://github.com/cloudflare/cloudflare-go/blob/b256903b71e0a2b9de8ef20ba704918f4d8a242b/zero_trust/accessapplication.go

[github-actions]

This functionality has been released in v0.96.0.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!