Bring token icons to the SDK from app

[pi0neerpat]

The app currently imports tokens from src/utils/tokens.ts
However they should be imported from the SDK, so we only need to make updates there for new collateral types.

Two patterns we could follow:

1. token icons are included as an entry for each token in the the token list object
2. OR, token icons are exported from a particular file

I prefer option 1