Hide floating action button when scrolling down and add scroll to top button to each screen

app/src/main/res/drawable/chevron_up.xml

@@ -0,0 +1,13 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="512dp"
+    android:height="512dp"
+    android:viewportWidth="512"
+    android:viewportHeight="512">
+  <path
+      android:pathData="M112,328l144,-144l144,144"
+      android:strokeLineJoin="round"
+      android:strokeWidth="48"
+      android:fillColor="#00000000"
+      android:strokeColor="#000"
+      android:strokeLineCap="round"/>
+</vector>