LibWeb: Apply scroll boxes offsets after painting commands recording

With this change, instead of applying scroll offsets during the
recording of the painting command list, we do the following:
1. Collect all boxes with scrollable overflow into a PaintContext,
   each with an id and the total amount of scrolling offset accumulated
   from ancestor scrollable boxes.
2. During the recording phase assign a corresponding scroll_frame_id to
   each command that paints content within a scrollable box.
3. Before executing the recorded commands, translate each command that
   has a scroll_frame_id by the accumulated scroll offset.

This approach has following advantages:
- Implementing nested scrollables becomes much simpler, as the
  recording phase only requires the correct assignment of the nearest
  scrollable's scroll_frame_id, while the accumulated offset from
  ancestors is applied subsequently.
- The recording of painting commands is not tied to a specific offset
  within scrollable boxes, which means in the future, it will be
  possible to update the scrolling offset and repaint without the need
  to re-record painting commands.

Tests/LibWeb/Ref/reference/scrollable-box-with-nested-stacking-context-ref.html

@@ -0,0 +1,28 @@
+<style>
+    #container {
+        width: 300px;
+        height: 500px;
+        overflow: auto;
+        position: relative;
+        border: 2px solid black;
+    }
+
+    .content {
+        background-color: lightblue;
+        height: 100%;
+    }
+
+    .box {
+        background-color: magenta;
+        width: 100px;
+        height: 50px;
+        position: absolute;
+        top: 0px;
+        right: 50px;
+    }
+</style>
+<div id="container">
+    <div class="content">
+        <div class="box"></div>
+    </div>
+</div>