Add visibility toggle of password input. Closes #2

client/src/lib/hooks/use-previous.js

@@ -0,0 +1,11 @@
+import { useEffect, useRef } from 'react';
+
+export default (value) => {
+  const prevValue = useRef();
+
+  useEffect(() => {
+    prevValue.current = value;
+  }, [value]);
+
+  return prevValue.current;
+};