Create a compliance test suite

[czechboy0]

We need a test suite that concrete client implementors would be encouraged to run as part of their test suite to ensure the basic functionality of the HTTP client behaves correctly.

This coincides with the base functionality that libraries can rely on.

In practice, library authors, when receiving an issue, would first ensure that the concrete client their adopter is using complies with the test suite, and only then spend time debugging the issue. As libraries cannot work reliably with arbitrarily non-compliant client implementations, and we want to avoid them reverting to depending on a concrete client to achieve desired reliability.

[xbhatnag]

Continuing work on this, #76 only sets up the server library

[czechboy0]

This issue still isn't resolved. It tracks building a compliance test suites that authors of the various HTTP client implementations can run on their implementation, and the test suite ensures the implementation is compliant with the protocol.

It needs to test things such as:

• trailers are delivered in both directions
• full bidirectional streaming works correctly