Adjust the theme to fix some dark mode issues (#193)

Author: Fabtron

ui/src/main/res/drawable/snabble_ic_plus.xml

@@ -91,12 +91,12 @@
             android:layout_height="wrap_content"
             android:layout_marginEnd="8dp">
 
-            <ImageView
+            <androidx.appcompat.widget.AppCompatImageView
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_gravity="center"
                 android:importantForAccessibility="no"
-                android:src="@drawable/snabble_ic_minus"
+                android:src="@drawable/snabble_ic_minus_content"
                 app:tint="?attr/colorOnSurface" />
 
             <com.google.android.material.button.MaterialButton
@@ -145,12 +145,12 @@
             android:layout_height="wrap_content"
             android:layout_marginStart="8dp">
 
-            <ImageView
+            <androidx.appcompat.widget.AppCompatImageView
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_gravity="center"
                 android:importantForAccessibility="no"
-                android:src="@drawable/snabble_ic_plus"
+                android:src="@drawable/snabble_ic_plus_content"
                 app:tint="?attr/colorOnSurface" />
 
             <com.google.android.material.button.MaterialButton

ui/src/main/res/layout/snabble_dialog_product_confirmation.xml

@@ -79,7 +79,7 @@
                         tools:src="@drawable/snabble_ic_payment_select_sepa"
                         android:importantForAccessibility="no" />
 
-                    <ImageView
+                    <androidx.appcompat.widget.AppCompatImageView
                         android:id="@+id/payment_chevron"
                         android:layout_width="7dp"
                         android:layout_height="7dp"
@@ -129,4 +129,4 @@
             android:layout_marginTop="12dp"
             android:layout_marginBottom="12dp"
             android:text="@string/Snabble.Shoppingcart.BuyProducts.selectPaymentMethod" />
-</merge>
+</merge>

ui/src/main/res/layout/snabble_view_checkout_bar.xml

@@ -90,11 +90,11 @@
     </style>
 
     <style name="Widget.App.SnackbarText" parent="Widget.MaterialComponents.Snackbar.TextView">
-        <item name="android:textColor">?attr/colorOnSurface</item>
+        <item name="android:textColor">?attr/colorOnSecondaryContainer</item>
     </style>
 
     <style name="ThemeOverlay.App.Snackbar" parent="">
-        <item name="colorOnSurface">?attr/colorSurface</item>
+        <item name="colorOnSurface">?attr/colorSecondaryContainer</item>
     </style>
 
 </resources>