fix(#7552): Fix notebook snapshot image annotations (#7555)

* fix: painterro import

* test(snapshotAnnotation): add minimal e2e test

* chore: add e2e test annotation

* fix: notebook snapshot test

* refactor: put `v-else` on template

* small changes to the test and a visual one

* additional a11y

* fix: html structure

* test(e2e): fix notebook snapshot tests

* Update documentation for file download and JSON testing

* Update stubs and add jpg/png export

* refactor(TimelistComponent): tidy up

---------

Co-authored-by: John Hill <john.c.hill@nasa.gov>

src/api/overlays/components/OverlayComponent.vue

@@ -20,7 +20,7 @@
  at runtime from the About dialog for additional information.
 -->
 <template>
-  <div class="c-overlay js-overlay">
+  <div class="c-overlay js-overlay" role="dialog" aria-modal="true" aria-label="Modal Overlay">
     <div class="c-overlay__blocker" @click="destroy"></div>
     <div class="c-overlay__outer">
       <button
@@ -34,9 +34,6 @@
           ref="element"
           class="c-overlay__contents js-notebook-snapshot-item-wrapper"
           tabindex="0"
-          aria-modal="true"
-          aria-label="Overlay"
-          role="dialog"
         ></div>
         <div v-if="buttons" class="c-overlay__button-bar">
           <button
@@ -61,7 +58,7 @@
 export default {
   inject: ['dismiss', 'element', 'buttons', 'dismissable'],
   emits: ['destroy'],
-  data: function () {
+  data() {
     return {
       focusIndex: -1
     };