[roll] Add a roll to dev recipe

The recipe merges the latest commit on a specified ref to dev. It
updates the VERSION file in refs/heads/dev to match the specified
ref or bumps the PRERELEASE version by 1 if they are already matching.


Change-Id: I2eddae8e35dcb9d90d3ea35df93316ac84e9db66
Reviewed-on: https://dart-review.googlesource.com/c/recipes/+/157960
Commit-Queue: Alexander Thomas <athom@google.com>
Reviewed-by: Karl Klose <karlklose@google.com>
6 files changed