Add squash and rebase stats to telemetry
## Problem to solve **Squash and merge** and **Rebase** are used by many customers, and we know that in some situations they can fail. We don't have sufficient data to quantify the rate of failure currently. ## Proposal Track the number of merge requests for which **squash and merge** and **rebase** are used to merge the merge request, and the number of times either are shown as available, but fail.
issue