Use Che Bot to provide factory link to PR in che-plugin-registry

[evidolob]

Now che-bot provide factory link for PR in che-theia:

I would be very nice if we have same for PR in che-plugin-registry, to have ability to test modifications in plugin meta.yaml more easy.

[evidolob]

cc @benoitf @slemeur

[che-bot]

Issues go stale after 180 days of inactivity. lifecycle/stale issues rot after an additional 7 days of inactivity and eventually close.

Mark the issue as fresh with /remove-lifecycle stale in a new comment.

If this issue is safe to close now please do so.

Moderators: Add lifecycle/frozen label to avoid stale mode.