Improve startup time for commands that do not operate on remotes

And for tab completion, by not unnessessarily statting paths to remotes,
which used to cause eg, spin-up of removable drives.

Got rid of the remotes member of Git.Repo. This was a bit painful.

Remote.Git modifies the list of remotes as it reads their configs,
so still need a persistent list of remotes. So, put it in as
Annex.gitremotes. It's only populated by getGitRemotes, so commands
like examinekey that don't care about remotes won't do so.

This commit was sponsored by Jake Vosloo on Patreon.

Assistant/WebApp/Gpg.hs

@@ -69,7 +69,7 @@ withNewSecretKey use = do
  -}
 getGCryptRemoteName :: UUID -> String -> Annex RemoteName
 getGCryptRemoteName u repoloc = do
-	tmpremote <- uniqueRemoteName "tmpgcryptremote" 0 <$> gitRepo
+	tmpremote <- uniqueRemoteName "tmpgcryptremote" 0 <$> Annex.getGitRemotes
 	void $ inRepo $ Git.Command.runBool
 		[ Param "remote"
 		, Param "add"