Added rudimentary support for automatically finding Microsoft Store version of Quake 3

Unlike the Steam and GOG support I'm not doing a registry search as I don't see anything in the registry that would show us the path. If we find more official ways to search for it later we can address that, in the meantime the path is just hardcoded to where it's installed by default.

code/sys/sys_win32.c

@@ -52,6 +52,9 @@ static char steamPath[ MAX_OSPATH ] = { 0 };
 // Used to store the GOG Quake 3 installation path
 static char gogPath[ MAX_OSPATH ] = { 0 };
 
+// Used to store the Microsoft Store Quake 3 installation path
+static char microsoftStorePath[MAX_OSPATH] = { 0 };
+
 #ifndef DEDICATED
 static UINT timerResolution = 0;
 #endif
@@ -222,6 +225,17 @@ char *Sys_GogPath( void )
 	return gogPath;
 }
 
+/*
+================
+Sys_MicrosoftStorePath
+================
+*/
+char* Sys_MicrosoftStorePath(void)
+{
+	Q_strcat(microsoftStorePath, MAX_OSPATH, "C:\\Program Files\\ModifiableWindowsApps\\Quake 3\\EN");
+	return microsoftStorePath;
+}
+
 /*
 ================
 Sys_Milliseconds