Add examples on how to register options to Commands

These examples show how to register options to SSH and REST
Commands in Gerrit via plugin.

example-sshCommandOption
example-restApiCommandOption

This requires the following extension:
https://gerrit-review.googlesource.com/#/c/80762/

Change-Id: I98db80d23bb5fb54bdd261180d46fcc873a3ac23
32 files changed