Support multiple git trailers

[rkotze]

Summary

Support multiple trailers that could be added to a commit message like:

• Signed-off-by:
• Reviewed-by:

Example cmd: git mob --type=si <author keys> all listed keys would apply Signed-off-by: trailer.

Questions

1. Should the keys be defined freely by the user in the git config or should it be stricter and owned by git mob?

Motivation

Help make it easy for everyone to use multiple types of trailers.

Tech Documentation

Git documentation about trailers
Stackoverflow Git trailers