fetch cause funding pool balances with minimal blockchain queries

[divine-comedian]

for two scenarios we need to fetch the balance of the cause funding pool on-chain

• checking if the cause should be sent to evaluation service
• check how much funding should be distributed from cause funding pool

in each cause we are making a separate blockchain query, which will get quite heavy as the amount of Causes grows..

we should find a way to make minimal calls to the blockchain to get required information to prevent the BE from running heavy queries