Add Icon Browser: set icon to macros

Add a dialog to browse application defined icons and user defined ones. Used to set icons on macro (this is stored in user settings).

implements #21619 (closed)

Screenshots

example of settings

[Icons]
Macros\1\icon=:/pqCore/Icons/pqDomain16.png
Macros\1\item=/home/nicolas/.config/ParaView/Macros/resetSession.py
Macros\2\icon=/home/nicolas/.config/ParaView/Icons/ParaView_Mark.svg
Macros\2\item=/home/nicolas/.config/ParaView/Macros/test.py
Macros\size=2

Images imported by user are copied inside a Icons directory under the user settings.

ParaView bundled resources start with :.