processor: Refactor TimestampedTracePiece

Chrome wants to add a few more counters to TrackEvents, which would
eventually also need a place in TimestampedTracePiece. Since TTP has
been growing a lot (and this contributed to increased memory usage in
trace processor), this patch refactors TimestampedTracePiece to make it
easier to add new data to only a subset of sorted events, while keeping
the TimestampedTracePiece of other events small.

Each TTP now has a type, and each type can store either inline or
heap-allocated supplemental data.

Bug: 123864183, 142557489
Change-Id: I050183c39bb24fadaad360886fee083577479328
diff --git a/BUILD b/BUILD
index 504f825..b9f8000 100644
--- a/BUILD
+++ b/BUILD
@@ -897,8 +897,8 @@
         "src/trace_processor/heap_profile_tracker.h",
         "src/trace_processor/importers/ftrace/ftrace_module.cc",
         "src/trace_processor/importers/ftrace/ftrace_module.h",
-        "src/trace_processor/importers/fuchsia/fuchsia_provider_view.cc",
-        "src/trace_processor/importers/fuchsia/fuchsia_provider_view.h",
+        "src/trace_processor/importers/fuchsia/fuchsia_record.cc",
+        "src/trace_processor/importers/fuchsia/fuchsia_record.h",
         "src/trace_processor/importers/fuchsia/fuchsia_trace_parser.cc",
         "src/trace_processor/importers/fuchsia/fuchsia_trace_parser.h",
         "src/trace_processor/importers/fuchsia/fuchsia_trace_tokenizer.cc",