Remove ProtocolType

[rukai]

This PR swaps all usages of ProtocolType to CodecState, since they are completely identical.
It then removes ProtocolType entirely.
For all the usecases I think the name CodecState makes the most sense so that is the name I am keeping.

[github-actions]

2 benchmark regressed. 0 benchmark improved. Please check the benchmark workflow logs for full details: https://github.com/shotover/shotover-proxy/actions/runs/7984709828

Found 7 outliers among 100 measurements (7.00%)
  5 (5.00%) high mild
  2 (2.00%) high severe
cassandra_codec/encode_system.local_query_v5_lz4_compression
                        time:   [1.4748 µs 1.5033 µs 1.5346 µs]
                        change: [+25.395% +27.895% +30.343%] (p = 0.00 < 0.05)
                        Performance has regressed.
--
                        Change within noise threshold.
Found 5 outliers among 100 measurements (5.00%)
  5 (5.00%) high mild
cassandra_codec/encode_system.local_result_v5_lz4_compression
                        time:   [48.982 µs 50.884 µs 52.482 µs]
                        change: [+20.606% +24.961% +29.560%] (p = 0.00 < 0.05)
                        Performance has regressed.

[github-actions]

2 benchmark regressed. 0 benchmark improved. Please check the benchmark workflow logs for full details: https://github.com/shotover/shotover-proxy/actions/runs/7997109946

Found 4 outliers among 100 measurements (4.00%)
  3 (3.00%) high mild
  1 (1.00%) high severe
cassandra_codec/decode_system.local_result_v5_no_compression
                        time:   [1.5171 µs 1.5407 µs 1.5630 µs]
                        change: [+28.697% +31.484% +34.211%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 1 outliers among 100 measurements (1.00%)
  1 (1.00%) high mild
cassandra_codec/encode_system.local_result_v5_lz4_compression
                        time:   [54.959 µs 55.752 µs 56.518 µs]
                        change: [+37.051% +42.220% +47.208%] (p = 0.00 < 0.05)
                        Performance has regressed.