fix(ocpp): check connector availability in RemoteStartTransaction auto-selection...

fix(ocpp): check connector availability in RemoteStartTransaction auto-selection (#1774)

* fix(ocpp): check connector availability in RemoteStartTransaction auto-selection

The OCPP 1.6 RemoteStartTransaction handler's connector auto-selection
(when connectorId is omitted) only checked transactionStarted and
reservation status but not administrative availability. This meant an
Inoperative connector could be selected, causing the request to be
rejected even when other Operative connectors were free.

Added isConnectorAvailable() check to the auto-selection loop, matching
the behavior already present in the OCPP 2.0 selectAvailableEvse().

* [autofix.ci] apply automated fixes

* Update tests/charging-station/ocpp/1.6/OCPP16IncomingRequestService-RemoteStartTransaction.test.ts

* Apply suggestion from @jerome-benoit

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Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Jérôme Benoit <jerome.benoit@piment-noir.org>