Adding tests for invalid arguments in start_batch

Bad framing tests

Hpack size tests

Add bad hpack frame tests

Refactored server.js and added a test to increase coverage

Removing code coverage for unreachable code.

Added explicit dependency on signet to gemspec

Make http2 interop tests always pass, and instead give a report

Add a test of invalid values to bad_client

Delete unused code

Marking unreachable code so that it doesn't get counted in code coverage

Add missing goto

Delete unused code

Delete unused code

Add test for grpc_get_well_known_google_credentials_file_path

add test for byte_buffer_copy

add ConfigureAwait(false) where needed