IVT currently is part of deps/

Modules for the IVT projects are currently in the deps folder (e.g. deps/ivt/core) but should be top-level according to the GitLab structure https://git.h2t.iar.kit.edu/sw/ivt. Also, all deps should be pinned to a specific version / git tag but for IVT this doesn't make sense as we have full control over the changes.

@dreher how should we do this?