ostree find-remotes requires write access to repository even if not pulling

[bauen1]

Run:

ostree find-remotes foo bar
error: Cannot write to repository: Permission denied


# Same for:
ostree find-remotes foo
ostree find-remotes

ostree find-remotes will error before even trying to validate the argument count.

And I don't see an immediate reason, why the act of only searching without actually pulling, should require write access to the repository.

This might be related to the undocumented --cache-dir option #1415