Fix flatpak build (#7283)

* Patch wxWidgets to automatically select dark theme variant (taken from
  Bambu slicer flatpak manifest)
* Drop python script that selected dark theme
* Add a patch to fix libslic3r build

flatpak/set-dark-theme-variant.py

@@ -1,85 +0,0 @@
-#!/usr/bin/env python3
-
-import Xlib
-import Xlib.display
-import time
-import subprocess
-import os
-import sys
-
-
-disp = Xlib.display.Display()
-root = disp.screen().root
-
-NET_CLIENT_LIST = disp.intern_atom('_NET_CLIENT_LIST')
-
-
-def set_theme_variant_by_window_id(id, variant):
-    # Use subprocess to call
-    # xprop and set the variant from id.
-    try:
-        s = subprocess.call(['xprop', '-f', '_GTK_THEME_VARIANT', '8u', '-set', '_GTK_THEME_VARIANT', variant, '-id', str(id)],
-                            stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
-        if s == 0:
-            return True
-        return False
-    except Exception as ex:
-        return False
-
-
-def set_theme_variant_from_win_id_collection(win_id_collection, variant):
-    # Loop though all of the collected
-    # window ids and set theme variant
-    for win_id in win_id_collection:
-        set_theme_variant_by_window_id(win_id, variant)
-
-
-def collection_win_id_from_wm_class_name(win_class_name):
-
-    collect = []
-
-    # Loop though all of the windows
-    # and collect id's those that match
-    # win_class: prusa-slicer
-    for win_id in root.get_full_property(NET_CLIENT_LIST, Xlib.X.AnyPropertyType).value:
-        try:
-            win = disp.create_resource_object('window', win_id)
-            if not win.get_wm_transient_for():
-                win_class = win.get_wm_class()
-                if win_id and win_class_name in win_class:
-                    collect.append(
-                        win_id) if win_id not in collect else collect
-        except Xlib.error.BadWindow:
-            pass
-
-    return collect
-
-
-if __name__ == '__main__':
-
-    if os.environ.get('PRUSA_SLICER_DARK_THEME', 'false') != 'true':
-        sys.exit(0)
-
-    # Listen for X Property Change events.
-    root.change_attributes(event_mask=Xlib.X.PropertyChangeMask)
-    # the class name of the slicer window
-    win_class_name = 'prusa-slicer'
-    # the variant to set
-    variant = 'dark'
-
-    start = time.time()
-
-    while True:
-        # collect all of the window ids
-        collect = collection_win_id_from_wm_class_name(win_class_name)
-        # give PrusaSlicer window 2 secs to
-        # collect the wanted window ids
-        # set the theme variant and exit
-        if time.time() - start <= 2:
-            # disp.next_event() blocks if no events are
-            # queued. In combination with while True
-            # it creates a very simple event loop.
-            disp.next_event()
-            set_theme_variant_from_win_id_collection(collect, variant)
-        else:
-            break