style: Transaction add button to floating button

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

+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0">
+
+    <path
+        android:fillColor="#000"
+        android:pathData="M19,13H13v6h-2v-6H5v-2h6V5h2v6h6v2z"/>
+
+</vector>
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app/src/main/res/layout/fragment_transactions.xml

-<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:tools="http://schemas.android.com/tools"
+<RelativeLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    android:padding="16dp">
+    android:layout_height="match_parent" >
 
-    <Button
+    <com.google.android.material.floatingactionbutton.FloatingActionButton
         android:id="@+id/button_addTransaction"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:text="+"
-        android:layout_alignParentBottom="true"
         android:layout_alignParentEnd="true"
-        android:layout_marginStart="16dp"
-        android:layout_marginBottom="48dp" />
+        android:layout_alignParentBottom="true"
+        android:layout_marginEnd="24dp"
+        android:layout_marginBottom="72dp"
+        android:src="@drawable/ic_plus"/>
 
 </RelativeLayout>
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