Remove status_helper as it is not needed any more

BUILD

CMakeLists.txt

Makefile

build.yaml

include/grpc++/impl/codegen/call.h

include/grpc++/impl/codegen/status_helper.h

tools/doxygen/Doxyfile.c++

tools/doxygen/Doxyfile.c++.internal

tools/run_tests/generated/sources_and_headers.json

vsprojects/vcxproj/grpc++/grpc++.vcxproj

vsprojects/vcxproj/grpc++/grpc++.vcxproj.filters

vsprojects/vcxproj/grpc++_test_util/grpc++_test_util.vcxproj

...vcxproj/grpc++_test_util/grpc++_test_util.vcxproj.filters

vsprojects/vcxproj/grpc++_unsecure/grpc++_unsecure.vcxproj

...s/vcxproj/grpc++_unsecure/grpc++_unsecure.vcxproj.filters

.../vcxproj/test/codegen_test_full/codegen_test_full.vcxproj

.../test/codegen_test_full/codegen_test_full.vcxproj.filters

...oj/test/codegen_test_minimal/codegen_test_minimal.vcxproj

...codegen_test_minimal/codegen_test_minimal.vcxproj.filters

...ojects/vcxproj/test/grpc_tool_test/grpc_tool_test.vcxproj