test: add EIP-7702 delegation transaction tests for

  pending state

  Add tests for EIP-7702 authorization and delegation transactions in
   pending/flashblocks state per #279.

  Tests:
  - Single delegation in pending flashblock
  - Multiple delegations in same flashblock
  - Receipt retrieval for EIP-7702 transactions
  - Delegation followed by execution across flashblocks

  test_eip7702_delegation_then_execution fails with overflow at
  state.rs:558 - this surfaces the sporadic behavior users reported.

  Closes #279

Author: madisoncarter1234