ServiceEnumerator: add configurable busyRepeatRequest retry count

[Copilot]

ServiceEnumerator previously allowed at most one retry on NRC 0x21 (busyRepeatRequest) via the boolean retry_if_busy_returncode flag. There was no way to control how many times the retry should be attempted.

Changes

• New kwarg retry_if_busy_returncode_count (int, default 3): maximum number of times a request is re-sent after receiving a busyRepeatRequest NRC. Validated as >= 0.
• Per-state retry counter _busy_repeat_request_count (defaultdict(int)): tracks in-flight busy retries per EcuState; incremented on each busy response, reset on a non-busy response or when the limit is exceeded.
• _evaluate_retry rewritten: directly manages _retry_pkt and the new counter instead of delegating to _populate_retry, which only supported a single retry.

Usage

# Default: retry up to 3 times on busyRepeatRequest
enumerator.execute(socket, state, retry_if_busy_returncode=True)

# Custom count
enumerator.execute(socket, state,
                   retry_if_busy_returncode=True,
                   retry_if_busy_returncode_count=5)

# Disable retries entirely (count=0 or the existing bool flag)
enumerator.execute(socket, state, retry_if_busy_returncode_count=0)