nost: xact audio hook (#823)

## Link to GitHub Issue or related Pull Request, if one exists
Fixes #822

## Description of change
Add hooks for `libxact.dll` which only Nostalgia uses for audio. Detect
cases where the game would fail to launch (wrong number of channels) and
log a warning / deferred log.

## Testing
tested 2024102200

src/spice2x/hooks/audio/xact.h

@@ -0,0 +1,5 @@
+#pragma once
+
+namespace hooks::audio::xact {
+    void init();
+}