mount: replace UNIT_DEPENDENCY_MOUNTINFO_OR_FILE with UNIT_DEPENDENCY_MOUNTINFO/UNIT_...

mount: replace UNIT_DEPENDENCY_MOUNTINFO_OR_FILE with UNIT_DEPENDENCY_MOUNTINFO/UNIT_DEPENDENCY_MOUNT_FILE

UNIT_DEPENDENCY_MOUNTINFO_OR_FILE was a bit strange as unlike the other flags
we don't know where the dependency came from exactly. Indeed its origin could
have been from the mount unit file or from /proc/self/mountinfo.

Instead this patch replaces UNIT_DEPENDENCY_MOUNTINFO_OR_FILE with 2 new
dependency flags: UNIT_DEPENDENCY_MOUNT_FILE and UNIT_DEPENDENCY_MOUNTINFO. The
former indicates that the dep is created from the unit file but unlike
UNIT_DEPENDENCY_FILE, it will be replaced by a dep with the
UNIT_DEPENDENCY_MOUNTINFO flag as soon as the kernel will make the mount
available in /proc/self/mountinfo.