This change adds the ability to manage garm-agent tools downloads. Users
can:
* Set an upstream releases page (github releases api)
* Enable sync from upstream. In this case, GARM will automatically download
garm-agent tools from the releases page and save them in the internal
object store
* Manually upload tools. Manually uploaded tools for an OS/arch combination
will never be overwritten by auto-sync. Usrs will need to delete manually
uploaded tools to enable sync for that os/arch release.
Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>
