Add missing IO benchmarks to benchmark configs for JS and LLVM

[jiribenes]

Three more IO benchmarks input_output/{server_client,networked_numbers,sender_receiver}.effekt can be used in benchmarking in Effekt plots given problem sizes in config_{js,llvm}.txt:
https://github.com/effekt-lang/effekt/blob/main/examples/benchmarks/config_js.txt
https://github.com/effekt-lang/effekt/blob/main/examples/benchmarks/config_llvm.txt

[phischu]

We could do this together with #1286