The registry package contained code to automatically set the CertsDir() path,
based on wether or not the daemon was running in rootlessmode. In doing so,
it made use of the `pkg/rootless.RunningWithRootlessKit()` utility.
A recent change in de6732a403 added additional
functionality in the `pkg/rootless` package, introducing a dependency on
`github.com/rootless-containers/rootlesskit`. Unfortunately, the extra
dependency also made its way into the docker cli, which also uses the
registry package.
This patch introduces a new `SetCertsDir()` function, which allows
the default certs-directory to be overridden, and updates the daemon
to configure this location during startup.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>