adjust block/uncle reward tests and add methods to pkg/geth blockchain and ethclient for direct fetching of eth balances

db/migrations/00046_update_block_and_uncle_reward_types.sql

@@ -0,0 +1,9 @@
+-- +goose Up
+ALTER TABLE blocks
+  ALTER COLUMN uncles_reward TYPE NUMERIC USING uncles_reward::NUMERIC,
+  ALTER COLUMN reward TYPE NUMERIC USING reward::NUMERIC;
+
+-- +goose Down
+ALTER TABLE blocks
+  ALTER COLUMN uncles_reward TYPE DOUBLE PRECISION USING uncles_reward::DOUBLE PRECISION,
+  ALTER COLUMN reward TYPE DOUBLE PRECISION USING reward::DOUBLE PRECISION;