Add bot indicator overlay to avatars (#1173)

* Add bot indicator overlay to avatars

* Add bot overlay to account list in search view

* Add preference for bot avatar overlay

app/src/main/java/com/keylesspalace/tusky/util/ViewDataUtils.java

@@ -63,6 +63,8 @@ public final class ViewDataUtils {
                         SmartLengthInputFilter.LENGTH_DEFAULT
                 ))
                 .setCollapsed(true)
+                .setIsBot(visibleStatus.getAccount().getBot())
+
                 .createStatusViewData();
     }