Turned load reporting into a plugin

BUILD

Makefile

build.yaml

src/core/ext/load_reporting/load_reporting.c

src/core/ext/load_reporting/load_reporting.h

src/core/ext/load_reporting/load_reporting_filter.c

src/core/plugin_registry/grpc_unsecure_plugin_registry.c

test/core/end2end/fixtures/h2_loadreporting.c

test/core/end2end/gen_build_yaml.py

tools/run_tests/sources_and_headers.json

tools/run_tests/tests.json

vsprojects/buildtests_c.sln

vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj

...jects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters

...dreporting_nosec_test/h2_loadreporting_nosec_test.vcxproj

...ng_nosec_test/h2_loadreporting_nosec_test.vcxproj.filters

...tures/h2_loadreporting_test/h2_loadreporting_test.vcxproj

..._loadreporting_test/h2_loadreporting_test.vcxproj.filters