Hop-to-hop compression

[Mallets]

This PR introduces support for transparent hop-to-hop compression.

[Mallets]

A synthetic performance test on this PR.

Target system:

Ubuntu 20.04 64-bit on AMD Ryzen 7 5800X 8-Core Processor

Compilation of pub/sub throughput examples

RUSTFLAGS='-C target-cpu=native' cargo build --release --example z_sub_thr --example z_pub_thr

Config stored in compression.json5:

{  transport: { unicast: { compression: { enabled: true, }, }, }, }

Running the examples (with 8 bytes payload):

RUST_LOG=debug taskset -c 1,3 ./target/release/examples/z_sub_thr -l tcp/127.0.0.1:7447 --no-multicast-scouting -n 4000000 -s 1000 -c compression.json5

and

RUST_LOG=debug taskset -c 0,2 ./target/release/examples/z_pub_thr 8 -e tcp/127.0.0.1:7447 --no-multicast-scouting -c compression.json5

Results with 8 bytes payload:

• Compression enabled:
  • Throughput: 4.27M msg/s.
  • Batch on the wire: 290 bytes
• Compression disabled:
  • Throughput: 4.38M msg/s
  • Batch on the wire: 65525 bytes

Results with 32K bytes payload:

• Compression enabled:
  • Throughput: 104K msg/s.
  • Batch on the wire: 292 bytes
• Compression disabled:
  • Throughput: 207K msg/s
  • Batch on the wire: 64025 bytes

[Mallets]

@yellowhatter can you please review this PR?
It touches some part of the code that is also touched by #601

[yellowhatter]

Approve!