Add "repository" option for custom repository path

[yelizariev]

There are usage cases when repository should be checked out in another repository (e.g. you copy files from one repo to another -- see workflow link below)

Tested here:

• workflow: https://github.com/yelizariev/addons-yelizariev/blob/275e1c789b681080543f4d8afc375fc539d60e21/.github/workflows/itpp-runbot-install.yml
• logs: https://github.com/yelizariev/addons-yelizariev/commit/275e1c789b681080543f4d8afc375fc539d60e21/checks?check_suite_id=351048628
• created commit: yelizariev/addons-yelizariev@7e8e26d

[stefanzweifel]

Thanks for your PR.

I will test this in an example project, until we have an automated test suite.
Will merge this in the next days.