P0 leak fixes: context/action menus destroyed on deactivate, config
callbacks unregistered in settings widgets, recorder and server signal
IDs stored and disconnected, bluetooth client closed and unsubscribed,
rfkill timer removed, seek timers cancelled, dropdown and options menus
freed, app name cache LRU-bounded.
Fix desktop 'Edit Widgets' and settings menu regressions by deferring
destroy out of Gtk signal handlers via GLib.idle_add.
Fix settings entry fields by connecting the activate signal explicitly
(Enter saves the value).
sankalp
d8696b9198