cfg: fix early game detection for Polaris Chord and MFG (#551)

## Link to GitHub Issue, if one exists


## Description of change
Some parts of the UI (e.g., Card tab) rely on early auto detection of
the game, which relies on file hints and not the game code. Two games
(PC and MFG) rely on directory presence and not file presence.

src/spice2x/launcher/launcher.cpp

@@ -1879,7 +1879,7 @@ int main_implementation(int argc, char *argv[]) {
             }
 
             // Polaris Chord
-            if (check_dll("kamunity.dll") && fileutils::dir_exists("game/svm_Data")) {
+            if (check_dll("kamunity.dll") && fileutils::file_exists("game/svm.exe")) {
                 avs::game::DLL_NAME = "kamunity.dll";
                 attach_io = true;
                 attach_pc = true;