Expose message list date separators to a11y

Signed-off-by: Peter Vágner <pvdeejay@gmail.com>

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -42,6 +42,7 @@ import android.net.Network;
 import android.net.NetworkCapabilities;
 import android.net.NetworkRequest;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Parcel;
@@ -551,6 +552,12 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                         canvas.translate(0, parent.getChildAt(i).getTop() - header.getMeasuredHeight());
                         header.draw(canvas);
                         canvas.restore();
+                        TextView tvDate = header.findViewById(R.id.tvDate);
+                        if (tvDate !=null) {
+                            view.setContentDescription(tvDate.getText().toString());
+                            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
+                                view.setAccessibilityHeading(true);
+                        }
                     }
                 }
             }