Create RPC delete collaborator

[nicholaspcr]

Summary

References #6314

Changes

• Add deleteCollaborator for: [clients, gateways, organizations, applications]
• Update tests to validate deleteCollaborator behavior

Testing

Update on unit tests and manual tests via the changes done on PRs that will be linked shortly.

Steps to reproduce and test the changes.

Since this will be merge only when all the subsequent PRs are approved, it means that the Console and CLI will be calling the new route. So in order to test just add and delete a collaborator to the entities mentioned in the changes section.

Nevertheless I will write some more detailed steps on the referenced issue.

Regressions

New rpc service and it does not change the behavior of the update route, there should not be any regressions.

Notes for Reviewers

Broke this into smaller PRs in order to avoid having huge PRs.

Didn't add anything on the CHANGELOG since this is mostly internal. It is probably worth adding that deletion of collaborators won't be able to be performed via the update route but that will only happen on a major release.

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• The steps/process to test this feature are clearly explained including testing for regressions.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.

[adriansmares]

LGTM in general.

[johanstokking]

Skimmed over it; you can merge