setVoiceJoinedState / setShareScreenButton updated only the inner NSButton's
title+image, but the text shown beneath a custom-view NSToolbarItem comes from
the item's label, not the button's title -- so the toolbar kept reading
"Join Voice" / "Share Screen Audio" after joining. Hold references to the
NSToolbarItems and update their label/paletteLabel alongside the button.
Talon
c5ad080692