Add entrypoints to luci-auth-ssh-* executables to fetch cipd packages
then run the binary.
Bug:b/435528916
Change-Id: Ic39b104d0ade8a65950fbbb755fa21c0b6514bb7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6864760
Auto-Submit: Jiewei Qian <qjw@chromium.org>
Reviewed-by: Chenlin Fan <fancl@chromium.org>
Commit-Queue: Chenlin Fan <fancl@chromium.org>