touch: restore wintouchemu, fall back to it when native touch hooks fail (#834)

## Link to GitHub Issue or related Pull Request, if one exists
Fixes #833

## Description of change
Last couple PRs - such as #820 #827 #828 - made the native touch hook &
touch injection using `InjectTouchInput` the default path, since it
performs much more reliably with both real touch screens and mouse (or
any other synthetic source).

However, user has reported that WINE lacks `InjectTouchInput` which
means this won't work.

As a fix, revive the old wintouchemu code. Native touch is still the
default, but under following circumstances:

1. if `-touchemuforce` is set, or
2. if any of the required Windows touch APIs are unavailable

then we fail over from native touch to wintouchemu code. 

For Linux, condition #2 would be hit during init, and gracefully switch
over.

Caveat: the poke code for IIDX and Nost will continue to require native
touch, I do not want to maintain two paths for this. This means that
iidx poke will stop working on Linux, unfortunately.

## Testing
Tested on Windows with `-touchemuforce` set. This is mostly reverting
Linux code path back to where we were last release, so this should just
work with wine.

src/spice2x/touch/native/nativetouchhook.h

@@ -15,7 +15,7 @@ namespace nativetouch {
 
     using TouchInputFilter = bool (*)(const NativeTouchEvent &event);
 
-    void hook(HMODULE module);
+    bool hook(HMODULE module);
     void refresh_contact_lifetime();
     void set_input_filter(TouchInputFilter filter);