Tint and resize import/export icons

Closes #6567
// FREEBIE

res/layout/import_export_fragment.xml

@@ -38,7 +38,8 @@
                        android:layout_marginStart="16dp"
                        android:layout_marginRight="32dp"
                        android:layout_marginEnd="32dp"
-                       android:src="?import_sms"/>
+                       android:src="@drawable/ic_message_white_24dp"
+                       android:tint="?attr/pref_icon_tint"/>
 
             <LinearLayout android:orientation="vertical"
                           android:layout_width="wrap_content"
@@ -80,7 +81,8 @@
                        android:layout_marginStart="16dp"
                        android:layout_marginRight="32dip"
                        android:layout_marginEnd="32dip"
-                       android:src="?plaintext_backup"/>
+                       android:src="@drawable/ic_content_copy_white_24dp"
+                       android:tint="?attr/pref_icon_tint"/>
 
             <LinearLayout android:orientation="vertical"
                           android:layout_width="wrap_content"
@@ -135,7 +137,8 @@
                        android:layout_marginStart="16dp"
                        android:layout_marginRight="32dp"
                        android:layout_marginEnd="32dp"
-                       android:src="?plaintext_backup"/>
+                       android:src="@drawable/ic_content_copy_white_24dp"
+                       android:tint="?attr/pref_icon_tint"/>
 
             <LinearLayout android:orientation="vertical"
                           android:layout_width="wrap_content"

res/values/attrs.xml

@@ -92,9 +92,6 @@
     <attr name="import_export_item_background_color" format="reference|color" />
     <attr name="import_export_item_background_shadow_color" format="reference|color" />
     <attr name="import_export_item_card_background" format="reference" />
-    <attr name="import_sms" format="reference" />
-    <attr name="encrypted_backup" format="reference" />
-    <attr name="plaintext_backup" format="reference" />
 
     <attr name="reminder_header_background" format="color"/>
 

res/values/themes.xml

@@ -181,9 +181,6 @@
         <item name="import_export_item_background_color">@color/import_export_item_background_light</item>
         <item name="import_export_item_background_shadow_color">@color/import_export_item_background_shadow_light</item>
         <item name="import_export_item_card_background">@drawable/clickable_card_light</item>
-        <item name="import_sms">@drawable/ic_message_black</item>
-        <item name="encrypted_backup">@drawable/ic_lock_light</item>
-        <item name="plaintext_backup">@drawable/ic_content_copy_light</item>
 
         <item name="menu_new_conversation_icon">@drawable/ic_add_white_24dp</item>
         <item name="menu_group_icon">@drawable/ic_group_white_24dp</item>
@@ -266,9 +263,6 @@
         <item name="import_export_item_background_color">@color/import_export_item_background_dark</item>
         <item name="import_export_item_background_shadow_color">@color/import_export_item_background_shadow_dark</item>
         <item name="import_export_item_card_background">@drawable/clickable_card_dark</item>
-        <item name="import_sms">@drawable/ic_message_white</item>
-        <item name="encrypted_backup">@drawable/ic_lock_dark</item>
-        <item name="plaintext_backup">@drawable/ic_content_copy_dark</item>
 
         <item name="fab_color">@color/textsecure_primary_dark</item>
         <item name="lower_right_divet">@drawable/divet_lower_right_light</item>