Add new natives to read/write on entity's private data based off class/member name available from gamedata files

modules/fakemeta/AMBuilder

@@ -13,6 +13,7 @@ binary.sources = [
   'engfunc.cpp',
   'fakemeta_amxx.cpp',
   'pdata.cpp',
+  'pdata_gc.cpp',
   'forward.cpp',
   'fm_tr.cpp',
   'pev.cpp',