Add a test that checks export version of project templates and test export archive

Description

When we bump import/export version in ImportExport class some number of tests is going to fail in the CI, without a meaningful description. It then takes a considerable amount of time, for someone not involved in developing import/export feature in the past, only to learn that we have test_project_export.tar.gz and project templates that need a version bump in VERSION as well.

I think we should add a test that will check export version in test_project_export.tar.gz against ImportExport::VERSION and print a meaningful message in the CI in case of a failure. /cc @jameslopez