tp: extract out track event methods from track tracker

This CL splits out all track event functionality from TrackTracker into
a new class called TrackEventTracker. This reduces the complexity of
TrackTracker significatly and removes some non-track related
functionality

Eventually, once we manage to refactor TrackEventTracker some more, we
will move all track creation back to TrackTracker.

There should be no functional changes in this CL.

Change-Id: I7ae223d2f4591e9e72c7ecc6a21ee3acf737beb2
diff --git a/Android.bp b/Android.bp
index 9516297..f124b24 100644
--- a/Android.bp
+++ b/Android.bp
@@ -7410,6 +7410,7 @@
     "src/trace_processor/importers/proto/track_event_module.cc",
     "src/trace_processor/importers/proto/track_event_parser.cc",
     "src/trace_processor/importers/proto/track_event_tokenizer.cc",
+    "src/trace_processor/importers/proto/track_event_tracker.cc",
     "src/trace_processor/trace_processor_context.cc",
     "src/trace_processor/trace_processor_storage.cc",
     "src/trace_processor/trace_processor_storage_impl.cc",