✨(frontend) introduce long press keyboard shortcut

Needed to support push to talk using the spacebar.
Introduce a utility hook. Will be called by the mic toggle
in the upcoming commits.

Inspired by Jitsi code.

src/frontend/src/features/shortcuts/useLongPress.ts

@@ -0,0 +1,47 @@
+import { useEffect, useRef } from 'react'
+
+export type useLongPressProps = {
+  keyCode?: string
+  onKeyDown: () => void
+  onKeyUp: () => void
+  longPressThreshold?: number
+}
+
+export const useLongPress = ({
+  keyCode,
+  onKeyDown,
+  onKeyUp,
+  longPressThreshold = 300,
+}: useLongPressProps) => {
+  const timeoutIdRef = useRef<ReturnType<typeof setTimeout> | null>(null)
+
+  useEffect(() => {
+    const handleKeyDown = (event: KeyboardEvent) => {
+      if (event.code != keyCode || timeoutIdRef.current) return
+      timeoutIdRef.current = setTimeout(() => {
+        onKeyDown()
+      }, longPressThreshold)
+    }
+
+    const handleKeyUp = (event: KeyboardEvent) => {
+      if (event.code != keyCode || !timeoutIdRef.current) return
+      clearTimeout(timeoutIdRef.current)
+      timeoutIdRef.current = null
+      onKeyUp()
+    }
+
+    if (!keyCode) return
+
+    window.addEventListener('keydown', handleKeyDown)
+    window.addEventListener('keyup', handleKeyUp)
+
+    return () => {
+      window.removeEventListener('keydown', handleKeyDown)
+      window.removeEventListener('keyup', handleKeyUp)
+    }
+  }, [keyCode, onKeyDown, onKeyUp, longPressThreshold])
+
+  return
+}
+
+export default useLongPress