Migrate to AndroidX (#2424)

* Migrate to AndroidX (automatic conversion by Android Studio)

* AndroidX dependency code updates

* Fix source preference reparenting

* fixes the androidx prefererences icon spacing issue

(cherry picked from commit b76a15d960ec2cdf771be16377db0348b66b3179)

* Fix source preference screen heading size/list padding

Co-authored-by: Carlos <cargo8005@gmail.com>

app/src/main/res/layout/recently_read_controller.xml

@@ -5,7 +5,7 @@
                 android:layout_height="match_parent"
                 android:orientation="vertical">
 
-    <android.support.v7.widget.RecyclerView
+    <androidx.recyclerview.widget.RecyclerView
         android:id="@+id/recycler"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
@@ -14,7 +14,7 @@
         android:clipToPadding="false"
         tools:listitem="@layout/recently_read_item">
 
-    </android.support.v7.widget.RecyclerView>
+    </androidx.recyclerview.widget.RecyclerView>
 
     <eu.kanade.tachiyomi.widget.EmptyView
         android:id="@+id/empty_view"
@@ -23,4 +23,4 @@
         android:layout_gravity="center"
         android:layout_height="wrap_content"/>
 
-</FrameLayout>
+</FrameLayout>