Auto-merge flag during PR creation

[bbednarek]

Description

It would be very helpful to add --auto-merge flag to turbolift create-prs command.

Motivation

In case of huge amount of repos it would be very convenient to enable auto-merge (if the repo has such function of course), so if all of the checks are green, then PR would be merged automatically.

[rnorth]

This sounds like a good suggestion, thank you. Would you like to raise a PR to add this feature?

[bbednarek]

@rnorth I am not familiar with go lang, but next week I plan to learn it, so I might give a try to raise a PR :)