Use multicall to update portfolio prices and values in real time

[hieronx]

The portfolio page displays balances and prices of the token holdings of a specific address. An example is https://tinlake.centrifuge.io/portfolio?address=0x683b73162ca9f344847c01d5040f07926b4d1378.

This data is retrieved from the subgraph, but the subgraph only updates the balances on a daily basis. See https://github.com/centrifuge/tinlake-subgraph/blob/main/src/domain/DailyPoolData.ts#L12

We want to fix this by using multicall to retrieve the real-time balance and price. An example usage of multicall in the tinlake UI codebase is here: https://github.com/centrifuge/apps/blob/main/tinlake-ui/ducks/pool.ts#L124 Ideally we should refactor this, likely by moving it into tinlake.js, but that's a larger item to tackle.