Improve RTL support (#964)

By making these changes, texts in relevant pages will appear currectly
in RTL layout.

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

@@ -16,6 +16,7 @@
         <androidx.core.widget.NestedScrollView
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
+            android:textDirection="anyRtl"
             android:layout_gravity="center">
 
             <LinearLayout

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

@@ -5,6 +5,7 @@
     android:id="@+id/accountCoordinatorLayout"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:textDirection="anyRtl"
     android:fillViewport="true">
 
     <com.google.android.material.appbar.AppBarLayout

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

@@ -19,6 +19,7 @@
             android:layout_height="wrap_content"
             android:clipChildren="false"
             android:orientation="vertical"
+            android:textDirection="anyRtl"
             android:paddingBottom="12dp">
 
             <TextView