Move online store defines closer to where they're used

It makes little sense to centralise the definitions for things like
Steam, GoG, etc.. These paths are only useful in the case where the user
has derived the data from such a store, has installed ioq3 in a separate
location, and we want it do be able to find said data. If a derivative
project has deployed (binaries and all) on e.g. Steam then for them
fs_basepath will already be correct, and fs_steampath is not useful.

code/qcommon/q_shared.h

@@ -34,8 +34,6 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   #define HOMEPATH_NAME_UNIX		".foo"
   #define HOMEPATH_NAME_WIN			"FooBar"
   #define HOMEPATH_NAME_MACOSX		HOMEPATH_NAME_WIN
-//  #define STEAMPATH_NAME			"Foo Bar"
-//  #define STEAMPATH_APPID         ""
   #define GAMENAME_FOR_MASTER		"foobar"	// must NOT contain whitespace
   #define CINEMATICS_LOGO		"foologo.roq"
   #define CINEMATICS_INTRO		"intro.roq"
@@ -49,10 +47,6 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   #define HOMEPATH_NAME_UNIX		".q3a"
   #define HOMEPATH_NAME_WIN			"Quake3"
   #define HOMEPATH_NAME_MACOSX		HOMEPATH_NAME_WIN
-  #define STEAMPATH_NAME			"Quake 3 Arena"
-  #define STEAMPATH_APPID			"2200"
-  #define GOGPATH_ID				"1441704920"
-  #define MSSTORE_PATH				"Quake 3"
   #define GAMENAME_FOR_MASTER		"Quake3Arena"
   #define CINEMATICS_LOGO		"idlogo.RoQ"
   #define CINEMATICS_INTRO		"intro.RoQ"