v0.12.3-testnet1

Improvements

• (x/ammswap) #346 Enhance creating swap pair.
• (x/ammswap) #349 Add unit test code for x/ammswap module.
• (x/ammswap) #352 Add rest api for x/ammswap module.
• (x/ammswap) #357 Optimize error messages, and add security check.
• (x/debug) #355 Check invariant in debug mode.
• (x/ammswap) #324 The latest upgrade supports x/ammswap module. Users could swap tokens, create/add/reduce liquidity based on OKExChain AMM swap.
• (x/mint) okx/cosmos-sdk#33 Inflation model is converted to deflation model. Mint token will be halved in three years by default.
• okx/cosmos-sdk@9e36816 The prefix of address is changed from okchain to okexchain.
• #328 Change okchain to okexchain. Binary file okchaind is changed to okexchaind, and okchaincli is changed to okexchaincli.