Adds support for qDOT and qUSDT vaults. Vaults can deposit DOT and/or USDT to the lending protocol on which they will receive qDOT and/or qUSDT. Instead of locking the qDOT/qUSDT in the lending market, they can use it as collateral for their Vaults as described here: https://docs.interlay.io/#/vault/multi-collateral?id=locking-lending-tokens-like-qdot-or-qusdt-as-collateral

This enables Vaults to earn interest from lending and vault operation at the same time.

Thresholds for qDOT
Secure: 155%
Premium redeem: 140%
Liquidation: 125%
Ceiling: 150k USD equivalent at current exchange rate

Thresholds for qUSDT
Secure: 155%
Premium redeem: 145%
Liquidation: 135%
Ceiling: 150k USD equivalent at current exchange rate