file_sys/control_metadata: Amend naming of members

Quite a bit of these were out of sync with Switchbrew (and in some cases
entirely wrong). While we're at it, also expand the section of named
members. A segment within the control metadata is used to specify
maximum values for the user, device, and cache storage max sizes and
journal sizes.

These appear to be generally used by the am service (e.g. in
CreateCacheStorage, etc).