TS-4759: Fix stream states management

[masaori335]

Below is the situation when this failure is happen.

1. h2spec sends a HEADERS frame with END_HEADERS flag and without END_STREAM flag.
2. TS returns a HEADERS frame and two DATA frames immediately. And TS set server side stream state closed.
3. h2spec sends RST_STREAM with a length other than 4 cotets.
4. TS ignores RST_STREAM to closed stream.

There are two problems.

• h2spec assumes server side stream state is open. ( This is fixed by h2spec v1.5.0 )
• At no. 2 , TS should change server side stream state to half-close (local).
  And send RST_STREAM frame to client and make state closed.

To fix this

• Change stream state to half-close (local) from idle or open when send a frame w/ END_STREAM flag
• Make send_a_data_frame to return HTTP2_SEND_A_DATA_FRAME_DONE when send DATA frame w/ END_STREAM flag
• Set stream state CLOSED when error is happen

[atsci]

FreeBSD build successful! See https://ci.trafficserver.apache.org/job/Github-FreeBSD/762/ for details.

[atsci]

Linux build successful! See https://ci.trafficserver.apache.org/job/Github-Linux/658/ for details.

[shinrich]

The changes look reasonable to me. Separate tracking sending EOS and receiving EOS seems like a good idea

[maskit]

Looks OK. I understand the necessity of doing this but I'm not thrilled adding more state flags to Http2Stream class. I can live with them but I hope they are managed in _state in the future.