**As an** OpenProject administrator
**I want** to be able to disable certain SCM types (e.g., linking \`:existing\` subversion repositories)
***So that** I can restrict my project administrators from linking external repositories.

### Acceptance criteria

- In the \`configuration.yml\`, not only \`:managed\` repositories can be toggled for each supported vendor, but also any other SCM type.

### Exemplary configuration

```
scm:
Git:
Begin of the insertiondisabled_types:End of the insertion Begin of the deletion types:End of the deletion
- :local
- :managed
manages: /tmp/git
Subversion:
Begin of the insertiondisabled_types:End of the insertion Begin of the deletion types:End of the deletion
- :existing Begin of the insertion
manages: /tmp/svnEnd of the insertion
``` Begin of the insertion

Should result in the following types available:

- Git: none (`:managed` disabled takes precedence over path set in `:manages`). Is hidden from selection for new repository creation
- Subversion: :managedEnd of the insertion