Swap: Modal

[joaquinsoza]

Add a review swap modal, same as the one in uniswap for now. should popup after clicking swap button, if #70 is already working the swap function should be called after this popup

i think this same modal changes after to a waiting for confirmation ( waiting for the user to sign the transaction in the wallet) and then it turns into a transaction submitted, so research how uniswap modal works, we should bring the logic to our app

Please refer to uniswap interface for the styled components and how the component is compose. I've been running this project locally to see the files and its workings.