fix: communicate expanded state of tooltips to screenreaders (#2322)

Co-authored-by: Nolan Lawson <nolan@nolanlawson.com>

src/routes/_components/Tooltip.html

@@ -3,6 +3,8 @@
 -->
 <span class="tooltip-button"
       aria-describedby="tooltip-{id}"
+      aria-expanded={shown}
+      aria-controls="tooltip-{id}"
       role="button"
       tabindex="0"
       on:mouseover="set({shown: true, mouseover: true})"