fix: Uniform audience parsing

[mitar]

Proposed changes

Making sure audience parsing in authorize flow is the same as in access flow. Consistency.

Edit: I extended that with few other cases and made it consistent across the board. Also stringx.Splitx is not used anymore now because calling RemoveEmpty is equivalent (but does more).

Checklist

• I have read the contributing guidelines
• I have read the security policy
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security vulnerability, I
  confirm that I got green light (please contact
  [email protected]) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation within the code base (if appropriate)

[aeneasr]

Could you add a regression test for this please?

[mitar]

Added test.

[aeneasr]

Thank you for the great contributions this week, @mitar!

[mitar]

BTW, could you make a release sometime soon? So that I can update stuff on our side.

[aeneasr]

Sorry about the delay - it's done! By the way, you can reference git hashes and branches in go.mod so need to wait to wait for releases :)

[mitar]

I know, but it is cleaner to have versions. :-)