Remove the legacy ViewSystem and some other tangentially related legacy code. (#5558)

Signed-off-by: bosnichd <bosnichd@amazon.com>

Code/Editor/Include/HitContext.h

@@ -19,7 +19,6 @@ class CBaseObject;
 struct IDisplayViewport;
 class CDeepSelection;
 struct AABB;
-class CCamera;
 
 #include <QRect>
 #include <platform.h>
@@ -68,8 +67,6 @@ struct HitContext
     QRect rect;
     //! Optional limiting bounding box for hit testing.
     AABB* bounds;
-    //! Optional camera for culling perspective viewports.
-    CCamera* camera;
 
     //! Testing performed in 2D viewport.
     bool b2DViewport;
@@ -120,7 +117,6 @@ struct HitContext
         rect = QRect();
         b2DViewport = false;
         view = 0;
-        camera = 0;
         point2d = QPoint();
         axis = 0;
         distanceTolerance = 0;

Code/Editor/Include/IDisplayViewport.h

@@ -14,7 +14,6 @@
 struct DisplayContext;
 class CBaseObjectsCache;
 class QPoint;
-class CCamera;
 struct AABB;
 class CViewport;
 
@@ -23,7 +22,6 @@ struct IDisplayViewport
 {
     virtual void Update() = 0;
     virtual float GetScreenScaleFactor(const Vec3& position) const = 0;
-    virtual float GetScreenScaleFactor(const CCamera& camera, const Vec3& object_position) = 0;
     virtual bool HitTestLine(const Vec3& lineP1, const Vec3& lineP2, const QPoint& hitpoint, int pixelRadius, float* pToCameraDistance = 0) const = 0;
 
     /**