Feature : add application to synchronize case from a remote server

[thomas-saigre]

This features adds a program feelpp_sync_case allowing to automatically synchronize export data from a remote server.
Some settings can be made in .feelppconfig (see the manual page in sync_case.adoc)
@prudhomm, this refers to a discussion we had on slack in April (https://feelpp.slack.com/archives/G92KZ23FZ/p1649929373589979,) and also discussion #1834

[skip toolboxes skip mor skip tests skip test skip python]

• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes?
• Have you successfully run the Feel++ testsuite with your changes locally?
• Have you written Doxygen comments in your contribution ?

Also : fixes the display of version on exec with option --version

• closes feelpp 0.110.0~rc.4: execs return wrong version number #1920

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