audio: create a wrapper for asio drivers (#731)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
Create `WrappedAsio`, similar to how we wrap `IAudioEndpoint`

So far, the wrapper does these things:

1. logging (for diagnosis, since iidx and gfdm don't produce any logs
when asio succeeds)
2. iidx32+ hack to work around refcount mismatch issue
3. sdvx valk cab hack to force 2-channel audio ("downmixing" by taking
only the front channels)
4. honor volume boost

As a result of `#2` the mempatch was removed from `iidx.cpp` since we
can tackle it cleanly in the hook. `#3` also removes the need for manual
patches.

Real downmixing is hard & expensive on the CPU so it was not
implemented.

## Testing
Tested iidx/sdvx/gfdm with xonar and flexasio

src/spice2x/launcher/launcher.cpp

@@ -72,6 +72,7 @@
 #include "games/museca/museca.h"
 #include "hooks/avshook.h"
 #include "hooks/audio/audio.h"
+#include "hooks/audio/asio_proxy.h"
 #include "hooks/audio/backends/wasapi/downmix.h"
 #include "hooks/debughook.h"
 #include "hooks/devicehook.h"
@@ -496,6 +497,9 @@ int main_implementation(int argc, char *argv[]) {
     if (options[launcher::Options::spice2x_SDVXAsioDriver].is_active()) {
         games::sdvx::ASIO_DRIVER = options[launcher::Options::spice2x_SDVXAsioDriver].value_text();
     }
+    if (options[launcher::Options::SDVXAsioTwoChannel].value_bool()) {
+        WrappedAsio::FORCE_TWO_CHANNELS = true;
+    }
     if (options[launcher::Options::spice2x_SDVXSubPos].is_active()) {
         auto txt = options[launcher::Options::spice2x_SDVXSubPos].value_text();
         if (txt == "top") {