Support to build and run benchmarks in byte mode

[shakthimaan]

• Adds run_config_byte.json to build and run benchmarks in byte mode.
• The benchmarks dune files have been updated to add the modes for native and byte, but, we need to use the run_config_byte.json file as follows:

$ USE_SYS_DUNE_HACK=1 SANDMARK_CUSTOM_NAME=5.00.0 BUILD_BENCH_TARGET=bytebench RUN_CONFIG_JSON=run_config_byte.json make ocaml-versions/5.00.0+stable.bench 

• The 5.00.0+stable.json file has been updated to February 24, 2022 commit.
• The CI has not been updated for the run_config_byte.json file as the execution is very slow compared to native runs.

[kayceesrk]

Should README also be updated with the information for how to run the bytecode benchmarks?

[shakthimaan]

The README has been updated, along with the necessary 5.0.0+trunk naming changes.