Refactors ButtonDropTarget to add extension data

Also fixes a bug where DeleteDropTarget was logging Remove instead of
Cancel.

Bug: 78793340
Test: Enable verbose logging and manual test
Change-Id: I0f0cfff070eab003ebb745292630bc6ce3243f4d
diff --git a/protos/launcher_log.proto b/protos/launcher_log.proto
index 7e15434..179f21d 100644
--- a/protos/launcher_log.proto
+++ b/protos/launcher_log.proto
@@ -104,9 +104,9 @@
   VERTICAL_SCROLL = 9;
   HOME_INTENT = 10; // Deprecated, use enum Command instead
   BACK_BUTTON = 11; // Deprecated, use enum Command instead
-  // GO_TO_PLAYSTORE
   QUICK_SCRUB_BUTTON = 12;
   CLEAR_ALL_BUTTON = 13;
+  CANCEL_TARGET = 14;
 }
 
 // Used to define the action component of the LauncherEvent.