Atom Tools: move boilerplate document management code to atom tools framework

• Moved all of the common save and load code to the document base class
• Moved undo and redo support to document base class but will probably extract to its own class or replace with one from AzTF
• Streamlined material editor, shader management console, and other tools with updated document code
• Cleaned up some of shader management console loading code, added support for saving, as well as getting and setting the shader variant list source data structure

Signed-off-by: Guthrie Adams <guthadam@amazon.com>

Gems/Atom/Tools/ShaderManagementConsole/Code/Source/Window/ShaderManagementConsoleWindow.cpp

@@ -61,8 +61,6 @@ namespace ShaderManagementConsole
         m_actionNew->setEnabled(false);
         m_actionSaveAsChild->setVisible(false);
         m_actionSaveAsChild->setEnabled(false);
-        m_actionSaveAll->setVisible(false);
-        m_actionSaveAll->setEnabled(false);
 
         OnDocumentOpened(AZ::Uuid::CreateNull());
     }