`orc update` should fail when none of the remotes have a given repository

[fcremo]

orc update does not throw an error if none of the configured remotes know about a given repo name. This also causes orchestra to search for binary archives named none_<recursive_hash>.tar.gz, because orchestra incorrectly assumes that the component does not have a HEAD commit. Orchestra shuld:

• fail when updateing and no remote contains a certain repo
• fail when trying to locate the binary archive for a component which has a repo name configured, but for which no remote info is available
  • alternatively, at a minimum, not use none as it does for components without a repo, but use unknown so the two can be distinguished

[fcremo]

Addressed by https://github.com/revng/revng-orchestra/pull/30, closing