CherryPick: add ability to customise cherry-picked commit message

CherryPick: add ability to customise cherry-picked commit message

Originally I wanted to support a feature similar to `-x` options from
https://git-scm.com/docs/git-cherry-pick#_options.
The idea was to append original commit hash in this format:
```
my original commit message

(cherry picked from commit 75355897dc28e9975afed028c1a6d8c6b97b2a3c)
```
This can be useful information in some integrations.
I decided to make it in a more generic way
and pass custom `CherryPickCommitMessageProvider` implementation.
One of the two default implementations can append original commit hash

Change-Id: Id664e8438b0b76c5cb9b58113887eec04aa6f611