Moves the merge script from the components repository over
to the shared dev-infra package. The merge script has been
orginally built for all Angular repositories, but we just
kept it in the components repo temporarily to test it.
Since everything went well on the components side, we now
move the script over and integrate it into the dev-infra package.
PR Close#37138
Creates a tool in ng-dev to determine the PRs which become conflicted
by merging a specified PR. Often the question is brought up of how
many PRs require a rebase as a result of a change. This script allows
to determine this impact.
PR Close#37051