Allow forcing "Only allow merge requests to be merged if the pipeline succeeds"

[timwsuqld]

We have a project that we have "Only allow merge requests to be merged if the pipeline succeeds" turned off because there are some cases where it's ok for certain developers to merge without waiting for a pipeline, or if a pipeline has failed.

However, we'd like marge-bot to only merge when the pipeline succeeds, so essentially a way to force "Only allow merge requests to be merged if the pipeline succeeds" for Marge. (A flag so the check always passes true when it checks if the target repository requires it)