This also tweaks EditorFileDialog to use the same shortcut,
while making it select the path text after focusing
(like in most file managers).
Ctrl + L / Cmd + Shift + G can also now be used to focus on the
property name in the project settings editor, as well in the
Input Map, Autoload, Shader Globals and Global Groups tabs.
This change introduces a new EditorThemeManager class
to abstract theme generatio and its subroutines.
Logic related to EditorTheme, EditorColorMap, and editor
icons has been extracted into their respective files with
includes cleaned up.
All related files have been moved to a separate folder to
better scope them in the project. This includes relevant
generated files as well.
* Adds an icon to all the input-adjacent add/remove buttons
* Adds a separator next to the action map "add" button
* Changes the Shader Globals editor to be consistent with the others
* Adds a clear button to the shader global name input
