More automated testing

Some testing currently exists: a few unit tests for small helper classes, as well as a few GUI / command line running tests. To extend the coverage, we should add at least one command line running test for every filter in open_iA. Potentially we can also test starting different tools (though this is depending on the [Common Project Files](https://github.com/3dct/open_iA/issues/46) feature).

Look at existing command line running tests in the codebase to understand the pattern. Identify all filters in open_iA (likely in a filters directory or module). For each filter, create a test that runs it via the command line with sample data. Check if there's a test framework already set up (e.g., Google Test). Ensure tests can be run automatically, possibly via CI. 'Done' means every filter has at least one command line test.

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