Add chains array param to user balance query

[danielmkm]

Add support for fetching user balances from multiple chains at once. As the balances leverage the token prices, we also implement support for multi chain token price fetching.

[danielmkm]

TODO: need to add support for fetching prices for multiple chains

[gmbronco]

lgtm – i just added a small change making it default to all chains if no chains are provided and an address filter, might be slightly easier to query.

[danielmkm]

lgtm – i just added a small change making it default to all chains if no chains are provided and an address filter, might be slightly easier to query.

Thanks for having a look @gmbronco. The way you did allChains will include fantom and optimism for balancer. You'd want to scope it to the project.

[gmbronco]

we changed the default fallback to the chainId passed in the header, so it's backwards compatibile.