The signal click of Close button is connected to "gtk_widget_hide".
As a result the window is hided, but still active and the whole
program renders unresponsive.
The Close button can appear for example if USSD_STATUS_IDLE comes
before a user press Cancel button in dialog window
(could be for example because of carrier timeout).
The "adw_dialog_close" function should be called instead.
Signed-off-by: knoppix <knoppix@4d2.org>
Part-of: <https://gitlab.gnome.org/GNOME/calls/-/merge_requests/776>
