Fix initial conditions in MRF when set-start-time is used

Issue/feature addressed

In the MRF method and when the initial condition is a file, the initial time is loaded from the restart file. This time may conflict with the command-line option --set-start-time, which causes a wrong start time in the MRF method. This is fixed in this merge request.

Proposed solution

Overwrite the loaded time if set-start-time is defined.

Implementation

Tests

Suggested reviewers

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Notes

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Checklist

• Functions and classes, or changes to them, are documented.
• User guide/documentation is updated.
• Changelog is updated.
• Suitable tests added for new functionality.
• Contributed code is correctly formatted. (See the contributing guidelines).
• License added to any new files.
• No extraneous files have been added (e.g. compiler output or test data files).