Add support for opening links in incognito mode on Linux & BSD (#4745)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

tests/resources/001-mimeapps.list

@@ -0,0 +1,32 @@
+thisshould=beignored
+# this is a comment
+
+[test]
+foo=bar
+# cool comment 😂 
+zoo=zar
+
+[Default Applications]
+lol=
+x-scheme-handler/http=firefox.desktop
+x-scheme-handler/https=firefox.desktop
+x-scheme-handler/chrome=firefox.desktop
+text/html=firefox.desktop
+application/x-extension-htm=firefox.desktop
+application/x-extension-html=firefox.desktop
+application/x-extension-shtml=firefox.desktop
+application/xhtml+xml=firefox.desktop
+application/x-extension-xhtml=firefox.desktop
+application/x-extension-xht=firefox.desktop
+
+[Added Associations]
+x-scheme-handler/http=firefox.desktop;
+x-scheme-handler/https=firefox.desktop;
+x-scheme-handler/chrome=firefox.desktop;
+text/html=firefox.desktop;
+application/x-extension-htm=firefox.desktop;
+application/x-extension-html=firefox.desktop;
+application/x-extension-shtml=firefox.desktop;
+application/xhtml+xml=firefox.desktop;
+application/x-extension-xhtml=firefox.desktop;
+application/x-extension-xht=firefox.desktop;

tests/resources/test-resources.qrc

@@ -0,0 +1,5 @@
+<RCC>
+  <qresource prefix="/">
+    <file>001-mimeapps.list</file>
+  </qresource>
+</RCC>