* multicaller: Support generic calls, not just eth_call

* multicaller: Support generic calls, not just eth_call

* multicaller: Implement balance_call

* multicaller: Split out a generic rpc stub for testing RPC requests other than eth_call

Test balance call

* multicaller: Move Block type to separate package to avoid dependency cycles for multicaller tests.

* fix(op-service): remove old balance call test

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Co-authored-by: refcell <abigger87@gmail.com>