Support circom with bazel rule

[chokobole]

I've just created a bazel rule for circom. It only supports r1cs and c at this moment, but still I think it's nice! You can think of it this like https://github.com/bazelbuild/rules_proto! If you're interested, i can move this repository to here and want it to be supported officially together!

See https://github.com/kroma-network/rules_circom and https://github.com/kroma-network/circomlib.