Fix #134418: Double clicking a file crashes Blender if load UI is off

Screen initialization is more context dependent than it used to be
because of region polling, so the context needs to be set up correctly.
Here was a case where the initialized window/screen passed to polling
didn't match what's in context (UI context was unset in fact).

Some asserts could be added to ensure data passed to screen
initialization matches context, but can do that separately.

Pull Request: https://projects.blender.org/blender/blender/pulls/135568

source/blender/editors/screen/screen_edit.cc

@@ -847,7 +847,13 @@ void ED_screen_refresh(bContext *C, wmWindowManager *wm, wmWindow *win)
 
 void ED_screens_init(bContext *C, Main *bmain, wmWindowManager *wm)
 {
+  wmWindow *prev_ctx_win = CTX_wm_window(C);
+  BLI_SCOPED_DEFER([&]() { CTX_wm_window_set(C, prev_ctx_win); });
+
   LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
+    /* Region polls may need window/screen context. */
+    CTX_wm_window_set(C, win);
+
     if (BKE_workspace_active_get(win->workspace_hook) == nullptr) {
       BKE_workspace_active_set(win->workspace_hook,
                                static_cast<WorkSpace *>(bmain->workspaces.first));