[FIP - 437] Add Predeposit Vault AMO to sfrxUSD strategies on Ethereum & Fraxtal

**Authors** Frax core team ## Summary This proposal amends FIP-434 by adding a new Predeposit Vault AMO to the sfrxUSD strategy framework. The Predeposit Vault AMO authorizes the sfrxUSD system to deploy approved underlying assets, each with an associated governance-approved cap, into verified predeposit vaults, such as those managed by Veda, Hourglass, and Concrete, that provide short-term, yield-bearing opportunities prior to full vault launches of new blockchains similar to what blockchain...