Fix caret move on iOS 17

There's an issue with iOS 17 where if you move the caret and then press
backwards, for example because you made a typo, the caret will jump to
its previous position. This is because on the onselectionchange event
the event handler doesn't see the caret move as a new DOM range. It thinks
the DOM range is the same as before and doesn't notify the registered
observers.

If we receive an onselectionchange event and the selection type is "Caret"
that means the caret moved and we should notify the observers, regardless
of whether the DOM range is the same as before.

src/trix/observers/selection_change_observer.js

@@ -49,7 +49,9 @@ export default class SelectionChangeObserver extends BasicObject {
 
   update() {
     const domRange = getDOMRange()
-    if (!domRangesAreEqual(domRange, this.domRange)) {
+    const caretMove = window.getSelection().type === "Caret"
+
+    if (!domRangesAreEqual(domRange, this.domRange) || caretMove) {
       this.domRange = domRange
       return this.notifySelectionManagersOfSelectionChange()
     }