This will allow us to import FunOrb caches without worrying about the
risk of collisions with the main set of RuneScape caches.
Signed-off-by: Graham <gpe@openrs2.org>
These will be used by the high-level cache API, where we don't want to
expose mutable versions of the group/file types as that would allow the
index/cache to get out of sync.
Signed-off-by: Graham <gpe@openrs2.org>