Fraxlend: Add support for FXS

Add FXS as a Borrowable/collateral asset on Fraxlend

Benefits for Fraxlend

Fxs is the core of Frax Finance, while a lot of the market circulating fxs tokens are locked in vefxs
a lot is still in circulation in med term holders (1-6 months)
who do not want to lock their fxs in vefxs as they want to be able to unwind/sell if needed
this group of people would also be interested in going long on FXS or use it as collateral
they can go long currently by going on ftx or binance
but this brings the problem of
1 putting your funds centralized
2 kyc and restrictions
3 no revenue to fraxlend
I believe that an FXS market on fraxlend would be one of the biggest revenue at the start of fraxlend compared to btc/eth(confirmed on fraxlend) as btc/eth has plenty of alternatives
while fxs doesn’t have many and anyone who has fxs future in mind would prefer fraxlend as the revenue circles back into fxs

Specification

  1. What is the link between the author of the FIP and the Asset?
    The author is an early investor/presale of frax finance who has locked his funds in vefxs/pools(frax/fxs)

2 Explain the positioning of the token in the Fraxlend ecosystem. Why would it be a good borrow or collateral asset?

I believe the participation on this token being added on fraxlend would be bigger than any other coin in the early start of fraxlend as there are no real alternatives on chain and fxs holders would have bias to fraxlend (due to revenue circling back to their fxs)