Other: Require trailing commas for multiline for most

Require trailing commas for multiline for arrays, objects, imports and
exports and disallow trailing commas for functions.
Do this by updating the ESLint config and fixing new complaints.

The reason for this change are the resulting future cleaner version
diffs.

Also see:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Trailing_commas
https://eslint.org/docs/latest/rules/comma-dangle

src/prefsModules/PrefsBoxOrderListBox.js

@@ -21,13 +21,13 @@ export default class PrefsBoxOrderListBox extends Gtk.ListBox {
                     "The box order this PrefsBoxOrderListBox is associated with.",
                     GObject.ParamFlags.READWRITE,
                     ""
-                )
+                ),
             },
             Signals: {
                 "row-move": {
-                    param_types: [PrefsBoxOrderItemRow, GObject.TYPE_STRING]
-                }
-            }
+                    param_types: [PrefsBoxOrderItemRow, GObject.TYPE_STRING],
+                },
+            },
         }, this);
     }