Missing API for user applications

Problem to solve

A non-admin user can create applications in the profile settings. However, this cannot be done by API calls. Currently the Applications API can only be used by admin-users.

Intended users

Non-admin user who want to automate application creation or who want to develop WebApps which themselves create WebApps, for example by forking a WebApp hosted as GitLab pages. Then for the forked WebApp a new application must be created with an adapted Callback URL.

Proposal

All functions in the Applications API should be duplicated so that there are additional versions for listing, creating and deleting applications of the currently authenticated user.