fix: enable removing access application custom attributes and claims

[BSFishy]

Removes the omitempty on Access application custom attributes. This allows an empty list to be passed to remove empty attributes, which would have otherwise been omitted.

closes #2837

Description

Removes the omitempty on Access application custom attributes.

Has your change been tested?

Using the script in #2837

Types of changes

What sort of change does your code introduce/modify?

• Bug fix (non-breaking change which fixes an issue)
• 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 ✅

[ajholland]

Can you do the same thing for the CustomClaims field? - it's the OIDC version of SAML CustomAttributes

[github-actions]

This functionality has been released in v0.102.0.

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