FIP-17: Add FRAX-SUSHI veFXS Gauge

Summary

Add a FRAX-SUSHI Sushiswap gauge to veFXS gauges.

Background & Motivation:

In an effort to diversify gauge weights and signal that veFXS gauges are not simply for 1 particular type of AMM, it is proposed to add a Sushiswap FRAX-SUSHI pair to the veFXS gauges. Sushiswap has supported FRAX since its early days by adding it to their Onsen menu back in February. Additionally, they have added FRAX pairs on Polygon and their other chain deployments.

SUSHI has a predominant amount of liquidity against ETH and almost none against any stablecoin. The system uses ETH to route in and out of stablecoins. While this is fine for them, it would be prudent to become their stablecoin of choice by providing a high amount of liquidity directly for SUSHI. Additionally, some Sushi chefs have expressed interest in supporting FRAX further if they get a gauge. This will also advance FRAX's multichain strategy with Sushiswap and opens the door for future cross-chain collaboration.

Lastly, having gauges on multiple AMMs shows credible neutrality that veFXS gauges are not only for Uni v3 pairs. This is important as FRAX seeks to win over other protocols to buy into the gauge system by being AMM-agnostic.

This proposal does not affect future proposals adding other gauges as planned such as other stable-stable Uni v3 pairs. Anyone in the community and other projects can proposal veFXS gauges on any AMM with FRAX and/or FXS being part of the pair.

For: Add FRAX-SUSHI veFXS Gauge

Against: Do nothing