Ensure that direct github app instalment without user on our side works

[evheny0]

By click of button in https://github.com/apps/deployqa

[nick-vyrko]

This is not possible without a User instance.

User has to exist because we need to create a user project role for the newly created project

Therefore when we install the github app, a project is not created and further PR creation calls a webhook, but it crashes due to project missing