Drop netty websocket implementation

[whyoleg]

Motivation:

• It was never released
• having it doesn't provide any benefits comparing to ktor implementation
• it's implementation is rather cumbersome and has a lot of configuration parameters because of full netty HTTP codec
• Mostly, we don't need even netty TCP implementation as ktor network performs on-par, but it's much easier to support it as TCP is easier

[github-actions]

Test Results

  961 files   -   8    961 suites   - 8   1h 4m 29s ⏱️ - 11m 30s
4 431 tests  -  48  4 039 ✅  -  36  392 💤  - 10  0 ❌  - 2 
8 121 runs   - 192  7 360 ✅  - 150  761 💤  - 40  0 ❌  - 2 

Results for commit 23ba2d5. ± Comparison against base commit cd1b7f8.

This pull request removes 48 tests.

io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ fireAndForget10[jvm]
io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ largePayloadFireAndForget10[jvm]
io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ largePayloadMetadataPush10[jvm]
io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ largePayloadRequestChannel200[jvm]
io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ largePayloadRequestResponse100[jvm]
io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ metadataPush10[jvm]
io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ requestChannel0[jvm]
io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ requestChannel16x256[jvm]
io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ requestChannel1[jvm]
io.rsocket.kotlin.transport.netty.websocket.NettyWebSocketSslTransportTest ‑ requestChannel200000[jvm]
…