Adding JSON caching for XPA info loading
Adding JSON caching for XPA info loading

The caching stops us from having to open the archives up, and it also
allows us to load the data using the faster JSON parser.  It results
in a 4 times performance boost over loading the YAML directly from the
XPA.

jlisee/xpkg,jlisee/xpkg,jlisee/xpkg