Make input and output editable

As a user, Andra redeemed OETH and then wanted to mint again. She saw that the input was "stuck" on OETH and couldn't find a way to change it to something she was now holding. Her intuition was to click the logo in the top left, then the Swap nav item expecting one of them to reset the form back to her original experience. She also tried refreshing the page. She did not know to click the arrow to flip the transaction nor click the output to change it to OETH.

We originally designed the OUSD dapp this way in an effort to communicate that OETH is required to be one side of the transaction. In other words, the dapp would not support swaps involving other tokens since that's what Uniswap and others are for. However, most users are accustomed to both the input and the output being editable on Uniswap and Curve. If we use the same dropdown element on both, we can still enforce the requirement that OETH (or OUSD) be involved.

I also suspect that the arrow is too subtle to do much good with the new theme, but that still isn't enough to make the form as intuitive as possible.

Our own way

The established way

Start at the Swap nav item and locate the form described in the issue. Compare its current input and output controls with the established examples, including the arrow interaction. Done means both sides are editable while the transaction still requires OETH or OUSD on one side, with the described reset and flip behavior working intuitively.