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/plugins/notebook/components/NotebookEmbed.vue

@@ -23,6 +23,7 @@
   <div
     ref="notebookEmbed"
     class="c-snapshot c-ne__embed"
+    :aria-label="`${embed.name} Notebook Embed`"
     @mouseover.ctrl="showToolTip"
     @mouseleave="hideToolTip"
   >