Update asset registry for LINK, SKY, LDO & wstETH

This proposal, if approved, will:

• Update asset registry for Chainlink (LINK)
• Update asset registry for Sky [previously MakerDAO] (SKY)
• Update asset registry for Lido (LDO)
• Update asset registry for Wrapped Staked ETH (wstETH)
• Add SKY as fee payment asset
• Add LINK as fee payment asset
• Add LDO as fee payment asset
• Add wstETH as fee payment asset

These assets are currently registered as external tokens - this referendum adds the missing on-chain asset information, makes them sufficient & adds them as fee payment assets