Fix keyboard support on the dropdown (#1073)

* Fix: dropdown now supports accessibility labels and keyboard controls

* Fix event propagation around the post dropdown

src/view/com/util/EventStopper.tsx

@@ -0,0 +1,22 @@
+import React from 'react'
+import {View} from 'react-native'
+
+/**
+ * This utility function captures events and stops
+ * them from propagating upwards.
+ */
+export function EventStopper({children}: React.PropsWithChildren<{}>) {
+  const stop = (e: any) => {
+    e.stopPropagation()
+  }
+  return (
+    <View
+      onStartShouldSetResponder={_ => true}
+      onTouchEnd={stop}
+      // @ts-ignore web only -prf
+      onClick={stop}
+      onKeyDown={stop}>
+      {children}
+    </View>
+  )
+}