E3-904 Update autosave asVerify generation

See https://gitlab.esss.lu.se/e3/wrappers/core/e3-sequencer/-/merge_requests/9 for some context. The point of this MR is to use the same mechanism as in that case to generate the binary asVerify, as it seems to me to be a more logically correct on (if not 100% ideal).

This also adds a small test to make sure that the binary has been built and runs.