Allow both error types for >2^60 in MAX_STREAMS

[martinthomson]

STREAM_LIMIT_ERROR is fine.
FRAME_ENCODING_ERROR is fine.

We just need to be consistent in mentioning both throughout.

Closes #3781.

[marten-seemann]

I'd prefer to not make this change. STREAM_LIMIT_ERRORs only occur when the peers tries to open a stream with a too high stream ID, not when the peer is granting you a higher stream budget.
As this stream ID doesn't even exist, this is clearly a FRAME_ENCODING_ERROR.

[martinthomson]

That's a reasonable position. That says that STREAM_LIMIT_ERROR is only for violations of a limit, not for mistakes in setting it. That keeps the blame firmly on one side of the fence.

I saw the opposite angle too: the frame type in CONNECTION_CLOSE does provide a way to disambiguate source. STREAM_LIMIT_ERROR+MAX_STREAMS is fairly clear.

[ianswett]

I agree with @marten-seemann in this case based on the principles we've previously outlined.