[feature] Add the ability to bookmark a node for later reference

[jmlitfi]

It would be useful to add a feature to the GUI enabling a user to bookmark nodes using the right click menu. These nodes could then be cached and ideally a symbol or highlighting is used to indicate which nodes / classes are bookmarked for easy reference. An option would then be added to the navigation menu to enable the user to jump to any of the bookmarked nodes. This information would need to be stored in the jadx or jobf file for cases when an app is being looked at over multiple days.