trace_processor: migrate metadata to macro tables

While doing this, we can also refactor a bunch of code in TraceStorage
into a dedicated metadata tracker.

Context: go/perfetto-tp-refactor
Bug: 135177627
Change-Id: Id612bc66ed62fd39b5dd156d7ab87e41d4fa064c

BUILD

diff --git a/BUILD b/BUILD
index 5699b8b..18a633e 100644
--- a/BUILD
+++ b/BUILD
@@ -755,6 +755,7 @@
         "src/trace_processor/tables/counter_tables.h",
         "src/trace_processor/tables/macros.h",
         "src/trace_processor/tables/macros_internal.h",
+        "src/trace_processor/tables/metadata_tables.h",
         "src/trace_processor/tables/profiler_tables.h",
         "src/trace_processor/tables/slice_tables.h",
         "src/trace_processor/tables/track_tables.h",
@@ -789,8 +790,6 @@
         "src/trace_processor/filtered_row_index.h",
         "src/trace_processor/gfp_flags.cc",
         "src/trace_processor/gfp_flags.h",
-        "src/trace_processor/metadata_table.cc",
-        "src/trace_processor/metadata_table.h",
         "src/trace_processor/process_table.cc",
         "src/trace_processor/process_table.h",
         "src/trace_processor/raw_table.cc",
@@ -930,6 +929,8 @@
         "src/trace_processor/importers/proto/track_event_tokenizer.cc",
         "src/trace_processor/importers/proto/track_event_tokenizer.h",
         "src/trace_processor/metadata.h",
+        "src/trace_processor/metadata_tracker.cc",
+        "src/trace_processor/metadata_tracker.h",
         "src/trace_processor/process_tracker.cc",
         "src/trace_processor/process_tracker.h",
         "src/trace_processor/slice_tracker.cc",