Use light/dark mode colors for image description text (#3003)

* Use light/dark mode colors for image description text

This is an accessibility issue -- in light mode (which should have dark text
on a light background) the text color was hardcoded to light grey and the
background color was a semi-transparent black.

Fixes https://github.com/tuskyapp/Tusky/issues/2983.

* Update app/src/main/res/drawable/ic_drag_indicator_horiz_24dp.xml

Co-authored-by: Konrad Pozniak <connyduck@users.noreply.github.com>

Co-authored-by: Konrad Pozniak <connyduck@users.noreply.github.com>

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

@@ -4,7 +4,7 @@
         android:topLeftRadius="6dp"
         android:topRightRadius="6dp" />
     <stroke
-        android:color="?attr/colorBackgroundAccent"
+        android:color="?attr/colorOutline"
         android:width="1dp" />
-    <solid android:color="#B3000000" />
+    <solid android:color="?attr/colorSurface" />
 </shape>

app/src/main/res/drawable/ic_drag_indicator_horiz_24dp.xml

@@ -4,6 +4,6 @@
     <size
         android:width="8dp"
         android:height="1dp" />
-    <solid android:color="?attr/colorBackgroundAccent" />
+    <solid android:color="?android:textColorTertiary" />
     <corners android:radius="1dp" />
 </shape>

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

@@ -70,7 +70,7 @@
                     android:paddingRight="8dp"
                     android:paddingBottom="8dp"
                     android:textAlignment="center"
-                    android:textColor="#eee"
+                    android:textColor="?android:textColorPrimary"
                     android:textSize="?attr/status_text_medium"
                     tools:text="Some media description which might get quite long so that it won't easily fit in one line" />
             </androidx.core.widget.NestedScrollView>