[venus] 把 tools/gen_cbor/main.go 中的代码移到 venus-devtool

[simlecode]

链服务模块 / Chain Service Components

• [X] venus
• [ ] venus-auth
• [ ] venus-gateway
• [ ] venus-messager
• [ ] venus-miner
• [ ] 文档 / docs

订单服务模块 / Deal Service Components

• [ ] venus-market
• [ ] 文档 / docs

算力服务模块 / Storage Power Service Components

• [ ] venus-sector-manager
• [ ] venus-worker
• [ ] 文档 / docs

描述 / Description

把 venus tools/gen_cbor/main.go 中的代码移到 venus-devtool/cborgen