Remove public dependency of DBManager on SQLite

The MR removes the last relics of direct use of SQLite in the GeoModelDBManager headers, so we can now have a PRIVATE dependency of GeoModelDBManager on SQLite.

This also solves the issues observed by @akraszna in !19 (closed)

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cc: @akraszna

enabled an automatic merge when the pipeline for 76f88c5c succeeds

mentioned in commit 35737bc6

merged

mentioned in merge request !19 (closed)

resolved all threads