[epiphany] Disable application manager action in app mode

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 619631a5804b075e2a0ebf2d90b49dd0ea5a76bc
Author: Jan-Michael Brummer <jan brummer tabos org>
Date:   Fri Jan 8 15:08:43 2021 +0100

    Disable application manager action in app mode
    
    WebApps shouldn't be able to enter the application manager and change other settings.
    Disable open-application-manager action along with all other web app actions.
    
    Fixes: https://gitlab.gnome.org/GNOME/epiphany/-/issues/1405

 src/ephy-window.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/ephy-window.c b/src/ephy-window.c
index cba7ac252..431f96742 100644
--- a/src/ephy-window.c
+++ b/src/ephy-window.c
@@ -3618,7 +3618,8 @@ static const char *disabled_actions_for_app_mode[] = {
   "encoding",
   "bookmark-page",
   "new-tab",
-  "home"
+  "home",
+  "open-application-manager"
 };
 
 static gboolean