Filters the toolbarButtons in redux depending on the visitor state instead of filtering them every time in mapStateToProps. This will prevent unnecessary rerenders of the toolbar.

Additionally:
 - Moves visitor buttons const from features/config in features/toolbox.
 - Removes dublicate functions isButtonEnabled and isToolbarButtonEnabled.
 - Adds more buttons to the visitor allowed buttons which functionality has been any way accessible trough shortcuts or somewhere else.
 - Enables customButtons to be visible for visitors.

The previous version of getToolbarButtons function was actually adding the custom buttons on every call to the config toolbarButtons array, effectively creating dublicates of every custom button. The PR fixes this issue.

Also now we will be running the getToolbarButtons calculation only when needed.

Extract keyboard shortcuts logic to custom hook