feat(sdk): implement BRC-20

[iamcrazycoder]

What this PR does / why we need it:

This PR implements the BRC-20 tokens experiment which is a theoretical clone of ERC-20 on Ethereum. While, ERC-20 is completely based on smart contracts -- BRC-20 works on consensus of brc-20 indexers that tracks and maintains balances and transfers.

BRC-20 works on 3 process flows:

1. Deploy: launch a new token on brc-20
2. Mint: mint tokens from the available supply
3. Transfer: transfer/trade tokens between two parties

All of the above 3 process flows have been implemented in this PR.

Note: There are many edge cases that haven't been tested yet, so please proceed to use this branch w/ caution.