contribute to foreign repositories via forks

[samuelstroschein]

Contributing via OAuth flows (see #136) does not work for external contributors or repositories a translator has no access to. An alternative for public repositories could be GitHub's fork functionality. The editor forks a public repository either on behalf of the user or by creating an inlang-fork/repository fork for all external contributors.

More ideas are welcome.

[samuelstroschein]

The editor forking on behalf of the user seems to be the better flow. Changes from different users happen in isolation and forks are understood.

Flowchart

1. Opening repository github.com/inlang/inlang in the editor.
2. If a fork for the user does not exist, the user is notified via a dialog with explicit consent that the repository is forked.
   2.1. The fork has a prefix like inlang-{repositoryName} to identify the fork on encountering 2 again.
   2.2. The fork is auto-synced with upstream see the documentation and this documentation.
   2.3. The user conducts changes in the fork.
   2.4. Once the user is done, the user is forwarded to github to manually contribute the changes upstream.

Note: Potential conflict with hardcoded branch of #220

[samuelstroschein]

closed with @255