To save rebuilding cigocacher on each CI job, build it on-demand, and
publish a release similar to how we publish releases for tool/go to
consume. Once the first release is done, we can add a new
tool/cigocacher script that pins to a specific release for each branch
to download.
Updates tailscale/corp#10808
Change-Id: I7694b2c2240020ba2335eb467522cdd029469b6c
Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>
