chore: Separate extensions by app (#3905)

extensions/twitch/stub/src/main/java/tv/twitch/android/feature/settings/menu/SettingsMenuGroup.java

@@ -0,0 +1,14 @@
+package tv.twitch.android.feature.settings.menu;
+
+import java.util.List;
+
+// Dummy
+public final class SettingsMenuGroup {
+    public SettingsMenuGroup(List<Object> settingsMenuItems) {
+        throw new UnsupportedOperationException("Stub");
+    }
+
+    public List<Object> getSettingsMenuItems() {
+        throw new UnsupportedOperationException("Stub");
+    }
+}

extensions/twitch/stub/src/main/java/tv/twitch/android/settings/SettingsActivity.java

@@ -0,0 +1,5 @@
+package tv.twitch.android.settings;
+
+import android.app.Activity;
+
+public class SettingsActivity extends Activity {}

extensions/twitch/stub/src/main/java/tv/twitch/android/shared/chat/util/ClickableUsernameSpan.java

@@ -0,0 +1,9 @@
+package tv.twitch.android.shared.chat.util;
+
+import android.text.style.ClickableSpan;
+import android.view.View;
+
+public final class ClickableUsernameSpan extends ClickableSpan {
+    @Override
+    public void onClick(View widget) {}
+}