test(ocpp): add B02/B03 boot notification behavior and E02 Cable-First transaction...

test(ocpp): add B02/B03 boot notification behavior and E02 Cable-First transaction tests

B02/B03 Pending/Rejected Boot Notification Behavior (11 tests):
- Store interval from Pending/Rejected responses
- State transitions: Pending→Accepted, Pending→Rejected, Rejected→Accepted
- Use interval as heartbeat when in Pending state
- Block message initiation when in Rejected state
- Preserve connector states during Rejected state
- Support configurable retry intervals

E02 Cable-First Transaction Flow (12 tests):
- Cable plug event sequencing and EV detection flow
- Connector status transitions (Available→Occupied)
- Full Cable-First transaction lifecycle
- Context-based trigger reason selection
- Multiple connector independence

All 273 tests pass.