ImguiAtomSystemComponent isn't guaranteed to initialize before ImGuiManager, which caused some issues.
Additionally, because we allow the user to configure ImGui's render resolution, I've refactored the window size override into a new OverrideRenderWindowSize API in ImGuiManager to decouple it from the target render resolution.
- Added pause/resume button to ImGui Profiler to pause/resume profiling
- Added showing pass execution timeline
- Change TimestampResult to include both begin tick and duration tick. Update some function names of TimestampResult.
- Update some functions names in Pass.
- Stop showing accumulated time for ParentPass.
- Fixed a crash issue with ImGuiManager which doesn't have default font.