Resizable Headers for Gem Catalog and Gem Repo Screen (#6885)

* Initial mostly working attempt at resizable headers

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Add const and constexpr to variables

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Add header tracking for buttons, display items based on header scrollbar position, fix some spacing issues

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Correct styling for adjustable header, and intending header section and alingned item content with header text

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Prevent header resizing larger than table width.

Signed-off-by: Alex Peterson <26804013+AMZN-alexpete@users.noreply.github.com>

* Fix resize graphical glitching

Signed-off-by: Alex Peterson <26804013+AMZN-alexpete@users.noreply.github.com>

* Remove unecessary qss

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Removed necessary headers

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Remove extra nl and old comment

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Address PR feedback

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Removed unused variables

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Change variable to constexpr

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Remove AUTOMOC from headers, set background color of Gem Catalog to 333333 and adjustable header to transparent

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Change to using update instead of repaint when sections are resized

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

* Change temp directory creation on for gradle

Signed-off-by: nggieber <52797929+AMZN-nggieber@users.noreply.github.com>

Co-authored-by: Alex Peterson <26804013+AMZN-alexpete@users.noreply.github.com>

Code/Tools/ProjectManager/project_manager_files.cmake

@@ -81,6 +81,8 @@ set(FILES
     Source/TemplateButtonWidget.cpp
     Source/ExternalLinkDialog.h
     Source/ExternalLinkDialog.cpp
+    Source/AdjustableHeaderWidget.h
+    Source/AdjustableHeaderWidget.cpp
     Source/GemCatalog/GemCatalogHeaderWidget.h
     Source/GemCatalog/GemCatalogHeaderWidget.cpp
     Source/GemCatalog/GemCatalogScreen.h