fix(local): show durable execution ARN as soon as the execution starts

[ParidelPooya]

sam local invoke printed the durable execution ARN only after the execution reached a terminal state, and otherwise logged it at DEBUG. That ARN is the only identifier sam local execution get, history and stop accept, so an execution that was still running -- suspended on a callback, waiting out a context.wait, or interrupted with Ctrl-C -- could not be inspected without re-running the invoke under --debug and reading it out of the log.

--durable-execution-name is not a way around it. The emulator builds the ARN from a pair of generated UUIDs and keeps the name only as metadata, so the execution commands answer "Execution not found" when given a name. Nothing else about a running execution is missing: GetDurableExecution and GetDurableExecutionHistory both return data mid-flight, so the ARN was the only gap.

The ARN is now printed as soon as start_durable_execution returns, before the wait begins, together with the get/history/stop commands that work from another terminal while the execution runs. That mirrors the service, which returns the ARN in the X-Amz-Durable-Execution-Arn response header of Invoke -- the same header this code already builds for start-lambda and start-api callers, which is why the message is gated to the CLI path by the existing _is_cli_context() check. The completion summary is unchanged, so a short execution now names its ARN twice: at the start, where it is needed in order to poll, and at the end alongside the result.

The suggested commands are left unquoted, matching the existing completion output. Once the emulator emits service-shaped ARNs containing $LATEST, both call sites will need quoting, and that belongs with the ARN format change rather than here.

This covers the first of the three options #9200 offers. Listing local executions and accepting --durable-execution-name in the execution commands are not addressed here.

Testing: 86 unit tests pass across tests/unit/lib/utils/test_durable_formatters.py and tests/unit/local/docker/test_durable_lambda_container.py, five of them new -- the formatter, _show_execution_started in CLI context, in HTTP context and with no ARN, and an ordering test that asserts through a get_durable_execution side effect that the ARN was already printed by the time the execution was first polled. The existing sync wait_for_result test now expects both secho calls, in order. black, ruff and mypy clean.

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