cfg: asio driver selector must list both 32-bit and 64-bit drivers (#734)

## Link to GitHub Issue or related Pull Request, if one exists
#730 

## Description of change
spicecfg is a 32-bit application. When it uses the ASIO SDK it only saw
the 32-bit drivers.

There are some ASIO drivers that have different names under 32-bit and
64-bit (Xonar AE is one of them)... so we have to manually scan the
registry and surface both the WOW32 and WOW64 nodes.

## Testing
<img width="329" height="309" alt="image"
src="https://github.com/user-attachments/assets/7abecf76-6835-4df5-8c2e-e7b425130f4c"
/>

Checked both 32-bit and 64-bit configurator, identical results.

src/spice2x/hooks/audio/asio_driver_scan.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+namespace hooks::audio {
+
+    struct AsioDriverScanEntry {
+        std::string name;
+        bool found_32bit = false;
+        bool found_64bit = false;
+    };
+
+    std::vector<AsioDriverScanEntry> scan_asio_drivers();
+}