tp: refactor JSON code to remove ifdefs, consolidate ingestion into args

This CL consolidates all ifdefs (similar to what recently happened with
gzip) into a single class for JSON related things.

It also moves the ingestion of json object into args into the utils
file to allow it to be reused.

Bug: 151432548
Change-Id: Iaeccf798fa6478377abc70ef1cb0a20e4e76913f
diff --git a/BUILD b/BUILD
index 0516a6e..bb9eef4 100644
--- a/BUILD
+++ b/BUILD
@@ -898,8 +898,6 @@
         "src/trace_processor/importers/json/json_trace_parser.h",
         "src/trace_processor/importers/json/json_trace_tokenizer.cc",
         "src/trace_processor/importers/json/json_trace_tokenizer.h",
-        "src/trace_processor/importers/json/json_trace_utils.cc",
-        "src/trace_processor/importers/json/json_trace_utils.h",
         "src/trace_processor/importers/json/json_tracker.cc",
         "src/trace_processor/importers/json/json_tracker.h",
         "src/trace_processor/importers/proto/android_probes_module.cc",
@@ -967,6 +965,8 @@
         "src/trace_processor/importers/fuchsia/fuchsia_trace_utils.h",
         "src/trace_processor/importers/gzip/gzip_utils.cc",
         "src/trace_processor/importers/gzip/gzip_utils.h",
+        "src/trace_processor/importers/json/json_utils.cc",
+        "src/trace_processor/importers/json/json_utils.h",
         "src/trace_processor/importers/ninja/ninja_log_parser.cc",
         "src/trace_processor/importers/ninja/ninja_log_parser.h",
         "src/trace_processor/importers/proto/args_table_utils.cc",