feat(search): keyboard-accessible search button (#1331)

* Use a `<button>` for search

* Fix search button styles to match preexisting styling

* Remove additional native button properties.

* Invoke search button on click or keyboard.

* Reorganize search button DOM hierarchy

* Restore focus to the search button when exiting the search overlay

* Run prettier on Search.tsx

quartz/components/scripts/util.ts

@@ -3,6 +3,7 @@ export function registerEscapeHandler(outsideContainer: HTMLElement | null, cb:
   function click(this: HTMLElement, e: HTMLElementEventMap["click"]) {
     if (e.target !== this) return
     e.preventDefault()
+    e.stopPropagation()
     cb()
   }