[Zk-study] Create a circuit with boojum

[thomas-nguy]

Similarly to zksync v1.4 circuit definition

https://github.com/matter-labs/era-zkevm_test_harness/tree/v1.4.0/circuit_definitions

Use the boojum library to create a simple circuit and test it https://github.com/matter-labs/era-boojum

[XinyuCRO]

A simple circuit using boojum library: https://gist.github.com/XinyuCRO/1705b1d8fce53a3f6a8245e64157233e

put the gist in the examples folder and use cargo run --example simple to run the script