DEX aggregator intergration

[Zergity]

Intergrate free DEX aggregator API and Contract so position can be opened by any token in the network. And vice versa: closing to any token.

1inch is not free

paraswap seem to be the best option: https://developers.paraswap.network/api/master

testing for: ETH <-> rETH

UTR Flow:

1. UTR TRANSFER 10 USDT to Helper
2. Helper approve 10 USDT to ParaswapRouter
3. Helper call ParaswapRouter.data (with recipient is UTR) to receive x WETH
4. UTR call Helper.swap to open position using x WETH

Execution Flow:

• write an UT to aggAndOpen(a position with TOKEN_R = WETH using USDT as input)
• construct the engine with aggregrator params
• call paraswap api to get target and data
• construct the UTR Flow above and staticcall the data to estimate amountOut