✨ Generic user based application config

**Is your feature request related to a problem? Please describe.**

For now there is no easy generic way to solve the following use case:

> ✨ Publish and secure multiple instances of the same application type with a single proxy provider (forward auth) and bind it to a single user.

Example:

- application instances
- `https://-codes-server.mylab.com`
- `https://-codes-server.mylab.com`
- `https://-codes-server.mylab.com`
- `https://-codes-server.mylab.com`

- users
- `userA`
- `userB`
- `userC`
- `userN`

**Describe the solution you'd like**

It would be awesome to have a way generic way solve the described use case with an minimal amount of repetitive config required.

Without such feature you now have to repeat these steps for each application instance like code-server:

- create a new proxy provider
- with single application type
- and external host `https://-codes-server.mylab.com`.
- create a new application
- provide app details
- select the provider
- activate the application in the embedded outpost
- bind the app to an individual user
- edit the app policy and select a user

**Describe alternatives you've considered**
Using the above described workaround

**Additional context**