RFE: Support Personal Access Token deletion using value

[JohnVillalovos]

In GitLab 15.0 they added the ability to delete a Personal Access Token (PAT) by value. Previously could only delete a PAT by the ID. But if you have a lot of PATs and want to delete one with a specific value it was difficult, unless you had maintained a document mapping PAT values to IDs.

New API:
https://docs.gitlab.com/ee/api/personal_access_tokens.html#using-a-request-header

Release notes: https://about.gitlab.com/releases/2022/05/22/gitlab-15-0-released/

In previous versions of GitLab, personal access tokens could be deleted only by the ID. Because none of the endpoints return an ID from a given value, you couldn’t delete a personal access token if you only had the token value. (This isn't technically true)

You can also now use the personal_access_tokens/self endpoint to revoke a PAT with a single request. The endpoint revokes the PAT used to make the request, making it easy to quickly revoke PATs in case of a leak.

[nejch]

@JohnVillalovos I looked at this some time ago and we basically already support it via:

gl.personal_access_tokens.delete("self")

gitlab personal-access-token delete --id self

Should we just document that? I don't know if it makes sense to add anything to ObjectDeleteMixin since that assumes you've already provided an ID, but in this case we want to delete before we know the ID. An alternative would maybe be a custom delete_self() method on managers. Would give a convenient gitlab personal-access-token delete-self command, but not sure it's worth it.