Change API enums to enum class, remove now redundant prefixing

* This gives a little nicer syntax, a bit better type safety, and also
  reflects better for SWIG bindings. Overall it's a minor change but
  better.
* We don't update the C# UI at all, since it's soon to be removed and
  not worth the effort/code churn.
* For now so we're ABI compatible with C#, all enums are uint32_t, but
  that is an obvious optimisation in future to reduce struct packing.
* We avoid 'None' as an enum value, because it's a reserved word in
  python so will cause problems generating bindings.

qrenderdoc/Windows/ConstantBufferPreviewer.cpp

@@ -28,7 +28,7 @@
 
 QList<ConstantBufferPreviewer *> ConstantBufferPreviewer::m_Previews;
 
-ConstantBufferPreviewer::ConstantBufferPreviewer(CaptureContext &ctx, const ShaderStageType stage,
+ConstantBufferPreviewer::ConstantBufferPreviewer(CaptureContext &ctx, const ShaderStage stage,
                                                  uint32_t slot, uint32_t idx, QWidget *parent)
     : QFrame(parent), ui(new Ui::ConstantBufferPreviewer), m_Ctx(ctx)
 {
@@ -67,8 +67,7 @@ ConstantBufferPreviewer::~ConstantBufferPreviewer()
   delete ui;
 }
 
-ConstantBufferPreviewer *ConstantBufferPreviewer::has(ShaderStageType stage, uint32_t slot,
-                                                      uint32_t idx)
+ConstantBufferPreviewer *ConstantBufferPreviewer::has(ShaderStage stage, uint32_t slot, uint32_t idx)
 {
   for(ConstantBufferPreviewer *c : m_Previews)
   {