[App] Add log level setting to partmesh.

See merge request ogs/ogs!3012

[PL/Output] Escape {} to fix bug in error message.

See merge request ogs/ogs!3013

Change of OGS version only affects frontpage and navigation tree.
The navigation tree is a single html embedded into every page.
This helps in better CDN caching and faster uploads on Netlify.

Is used by the Doxygen job to populate the git version info.