Eliminate the DispatchCommon class (#12389)

## Summary of the Pull Request

Other than the `s_ResizeWindow` function, the `DispatchCommon` class was
just a couple of static functions indirectly calling the `ConGetSet`
interface. So by moving the `s_ResizeWindow` implementation into the
`ConhostInternalGetSet` class, we could easily replace all usage of
`DispatchCommon` with direct calls to `ConGetSet`.

## PR Checklist
* [x] Closes #12253
* [x] CLA signed.
* [ ] Tests added/passed
* [ ] Documentation updated.
* [ ] Schema updated.
* [x] I've discussed this with core contributors already. Issue number
where discussion took place: #12253

## Validation Steps Performed

I've manually confirmed the resizing operations still work as expected.
The other functions are harder to test, but were trivial replacements.

src/host/PtySignalInputThread.cpp

@@ -8,7 +8,6 @@
 #include "output.h"
 #include "handle.h"
 #include "../interactivity/inc/ServiceLocator.hpp"
-#include "../terminal/adapter/DispatchCommon.hpp"
 
 using namespace Microsoft::Console;
 using namespace Microsoft::Console::Interactivity;
@@ -137,9 +136,9 @@ void PtySignalInputThread::ConnectConsole() noexcept
 // - <none>
 void PtySignalInputThread::_DoResizeWindow(const ResizeWindowData& data)
 {
-    if (DispatchCommon::s_ResizeWindow(*_pConApi, data.sx, data.sy))
+    if (_pConApi->ResizeWindow(data.sx, data.sy))
     {
-        DispatchCommon::s_SuppressResizeRepaint(*_pConApi);
+        _pConApi->SuppressResizeRepaint();
     }
 }