Remove C++ code from our side

As part of the milestone "The Great Deprecation ": https://gitlab.idiap.ch/groups/bob/-/milestones/4#tab-issues, we intend to remove from the bob "umbrella" some C++ dependencies we maintain.

With this we expect an easier maintenance and release cycle

We need to remove from this package traces of

• bob.ip.gabor
• bob.ip.base
• bob.blitz
• bob.core

ping @mguenther, @amohammadi, @flavio.tarsetti, @ydayer, @andre.anjos