[OUSD] Launch new convex strategy

I propose rolling out a new Convex Strategy with a $300,000 starting allocation.

Convex

Convex is a layer on top of Curve pools to boost yields by increasing CRV rewards via vote locked veCRV. Using Convex should earn about 60% more than directly using Curve's 3Pool, and be a higher yield than the current lending pool strategies OUSD uses.

After a community vote to build a Convex strategy for OUSD, the a new Convex strategy is ready for deployment. Origin core team member Yu-Pan has written the majority of the code, with contributions from myself (dvf) and Tom Linton.

Pull request for the new strategy is here: https://github.com/OriginProtocol/origin-dollar/pull/768

Proposal

The rollout process would be:

• Deploy and verify contracts.
• Governance actions to add the new strategy to the vault, with support for DAI, USDC, and USDT.
• A mainnet fork testing period for simulations against the actual deployed contracts.

With approval from this proposal:

• A one week shakeout period with $100,000 each of DAI, USDC, and USDT allocated to the strategy.

Towards the end of this shakeout period, everyone can evaluate yield and decide on the next allocation amount.