eth: add MATIC token on Ethereum network

[buck54321]

Related to #2974. Users are withdrawing MATIC as a token on the Ethereum network. In lieu of a 3-tx solution that would 1) approve the migration contract, 2) migrate MATIC to POL on Ethereum, and 3) bridge POL to the Polygon network, we'll just give them access to their MATIC tokens by adding the asset.

From there, I see three outs for the user

1. We could create a MATIC@Ethereum-POL market
2. They could send their MATIC to e.g. Metamask, and optionally convert it to something we can use using e.g. Uniswap
3. If they have a CEX that accepts MATIC deposits as tokens on Ethereum, they can send it to their exchange.