Restore valid single-root LogConfig.xml format

[Copilot]

LogConfig.xml became invalid after adding new observer options because the file ended up with two top-level elements. This change restores a valid XML structure without changing the intended logging configuration behavior.

• XML format

  • Keep <simulators> as the single document root.
  • Move timestampedFilenames and floatingPointPrecision onto that root as attributes.

• Observer config parsing

  • Read the new logging options from the <simulators> root element.
  • Preserve existing simulator/variable parsing behavior.

• Regression coverage

  • Extend the config-based observer test to verify the root-level settings are still applied, including fixed filenames and configured numeric precision.

<simulators
    xmlns="http://opensimulationplatform.com/LogConfig"
    timestampedFilenames="false"
    floatingPointPrecision="1">
    <simulator name="slave" decimationFactor="20">
        <variable name="realOut"/>
        <variable name="intOut"/>
        <variable name="stringOut"/>
    </simulator>
</simulators>

• Fixes LogConfig.xml format is invalid #799

[restenb]

@copilot the changes broke one of the tests, investigate the cause and fix this.

[Copilot]

@copilot the changes broke one of the tests, investigate the cause and fix this.

Fixed in 9f84fee. The failing assertion was reading slave.csv before the observer had closed/flushed the file, so I updated the test to stop the observer before reading the log file. I also re-ran cpp_file_observer_logging_from_config_test in CI-like shared and static builds, and it passed in both.

[eidekrist]

Wunderbar!