Tests: WebSocket and CONNECT over HTTP/2 and HTTP/3

[liudongmiao]

Proposed changes

Tests for WebSocket over HTTP/2 and HTTP/3 using extended CONNECT, and for plain CONNECT tunnels over HTTP/2 and HTTP/3. Verify changes in PR: nginx/nginx#1683

• h2_proxy_websocket.t, h3_proxy_websocket.t follow proxy_websocket.t. They cover the handshake nginx synthesizes for the upstream, the response headers it drops, accept_extended_connect off, :protocol on a request that is not CONNECT, and the SETTINGS advertisement.
• h2_tunnel.t, h3_tunnel.t follow tunnel.t, with tunnel.t's authority matrix, minus the HTTP/1.0 case, plus a zero port, a missing authority, :scheme and :path.
• h2.t is updated because CONNECT carrying :scheme and :path is now rejected as malformed with 400 instead of 405, and 405 moves to a conforming CONNECT.

Test results

Against the source patch all 268 assertions pass. The wider run over the HTTP/2, HTTP/3, websocket, tunnel and proxy upgrade tests passes as well, 1545 assertions across 75 files.

Against nginx master without the patch the two websocket files skip, as master does not have the directives their configuration uses. h2.t fails 2 assertions and each tunnel file fails 5, so this needs nginx/nginx#1683 first.

The two tunnel files also pass unchanged against nginx/nginx#1277, a different implementation of plain CONNECT over HTTP/2 and HTTP/3, so they are not tied to either one.

Checklist

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• I have read the contributing guidelines.
• I have signed the F5 Contributor License Agreement (CLA).
• If applicable, I have added tests that prove my fix is effective or that my feature works.
• If applicable, I have checked that any relevant tests pass after adding my changes.
• I have updated any relevant documentation (README.md and/or CHANGELOG.md).