Profiling: Add more instrumentation

Adds new instrumentation macros throughout the codebase, using the
visualizer to find where current instrumentation is lacking using the
shadowed sponza sample + editor. Some notes from exploring:

- We spend ~5ms in CullingScene: BeginCulling
- PipelineStateCache: Compact usually 1ms
- CompileImageBarriers takes most of the time in CompileResourceBarriers

Signed-off-by: Jacob Hilliard <jhlliar@amazon.com>

Gems/Atom/RPI/Code/Source/RPI.Public/Pass/PassSystem.cpp

@@ -298,6 +298,7 @@ namespace AZ
 
         void PassSystem::ProcessQueuedChanges()
         {
+            AZ_ATOM_PROFILE_FUNCTION("RPI", "PassSystem: ProcessQueuedChanges");
             RemovePasses();
             BuildPasses();
             InitializePasses();
@@ -313,7 +314,11 @@ namespace AZ
 
             m_state = PassSystemState::Rendering;
             Pass::FramePrepareParams params{ &frameGraphBuilder };
-            m_rootPass->FrameBegin(params);
+
+            {
+                AZ_ATOM_PROFILE_TIME_GROUP_REGION("RPI", "Pass: FrameBegin");
+                m_rootPass->FrameBegin(params);
+            }
         }
 
         void PassSystem::FrameEnd()