Move images used in specs into subdirectories that bikeshed echidna will automatically package.

(Also move a few *out* of such directories, in the case of css-layout-api.)

Fixes more of w3c/csswg-drafts#7505.

Author: dbaron

css-animation-worklet-1/Overview.bs

@@ -704,7 +704,7 @@ interface WorkletAnimation : Animation {
 
 
 <figure>
-  <img src="img/WorkletAnimation-timing-model.svg" width="600"
+  <img src="images/WorkletAnimation-timing-model.svg" width="600"
     alt="Overview of the WorkletAnimation timing model.">
   <figcaption>
     Overview of the worklet animation timing model.

css-animation-worklet-1/README.md

@@ -115,7 +115,7 @@ instance that represent this particlar animation and then on each animation fram
 `animate` function to determine the local time which ultimately drives the keyframe effect.
 
 
-![Overview of the WorkletAnimation Timing Model](img/WorkletAnimation-timing-model.svg)
+![Overview of the WorkletAnimation Timing Model](images/WorkletAnimation-timing-model.svg)
 
 Here the same simple example but using Animation Worklet instead.
 
@@ -662,4 +662,4 @@ the most recent version.
 [input-for-worker]: https://discourse.wicg.io/t/proposal-exposing-input-events-to-worker-threads/3479
 [group-effect]: https://w3c.github.io/web-animations/level-2/#the-animationgroup-interfaces
 [group-effect-changes]: https://github.com/yi-gu/group_effects
-[scroll-timeline]: https://wicg.github.io/scroll-animations/#scrolltimeline
+[scroll-timeline]: https://wicg.github.io/scroll-animations/#scrolltimeline

css-animation-worklet-1/img/WorkletAnimation-timing-model.svg renamed to css-animation-worklet-1/images/WorkletAnimation-timing-model.svg

@@ -818,7 +818,7 @@ box</b>, before transform or positioning (e.g. if a fragment is [=relatively pos
 been applied.
 
 <figure>
-    <img src="img/layout-fragment-offsets.png" width="800"
+    <img src="images/layout-fragment-offsets.png" width="800"
       alt="An example of position a fragment in different writing modes.">
     <figcaption>
         A simple visualization showing positioning a {{LayoutFragment}} using
@@ -1255,7 +1255,7 @@ The {{LayoutEdges/inline}}, and {{LayoutEdges/block}} on the {{LayoutEdges}} obj
 attributes which represent the sum in that direction.
 
 <figure>
-    <img src="img/edges.png" width="800"
+    <img src="images/edges.png" width="800"
       alt="An example of layout edges.">
     <figcaption>
         A visualization showing the {{LayoutEdges}} object for a [=box=] with different sized