Add methods for Gerrit CR upload

The patch adds git and gerrit methods to
upload CR to Gerrit using pipelines.
Git`s "commitGitChanges" method has been
modified to support "-- amend" option.

Change-Id: I6f61784d0edf956418b033aae2407f1f868d5067
Related-PROD: PROD-30632
2 files changed