Add `contract` module in kuai project

[Keith-CY]

Document: #52

[Keith-CY]

Since the contract model is almost ready in kuai with PR #69, we can start the work of integrating ckb contract into the kuai

The integration should cover

1. compile/test/deploy contract: Integrate development workflow of contract #52
2. generate an SDK based on contract model: Feat contract #69

[Keith-CY]

For the second part

generate an SDK based on contract model: #69

We need a brainstorm and output some technical designs to discuss