- Implemented the PipeReader implementation and override the method on Pipe.
- The Pipe implementation has some caveats. Calling ReadAtLeast messes with the pipe back pressure since it's trying to prevent deadlocks. This means that if ReadAsync is called with a big threshold, the writer will write as fast as it can ignoring the PauseThreshold up until the reader is unblocked. In a sense, the call to ReadAtLeast async overrides the pause threshold for that one read.
- Added tests
- Added missing StreamConformance tests to the solution so it would build

- Flip the reading state off when we decide not to accept the read