On `git cl upload` and when running a command on all deps
using `gclient` in a non-Cog env, prints/logs a warning if git
should be updated. Non-blocking; command should still be
attempted as usual.
Bug: b/360206460
Change-Id: I8ebef4cb8b520124bc34ade7f0f2179874b470a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5874690
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>
Commit-Queue: Anne Redulla <aredulla@google.com>