[meta,cmake] Restructure project and introduce CMake tooling

Rearrange project to conform to current best-practices in modern C++ repo organization.

Introduce initial configuration file for the CMake meta-build system, based on the restructured organization.

.gitlab-ci.yml

-image: gitlab-registry.cern.ch/scouting-demonstrator/scouting-docker-images/scdaq-builder-1.0.5
+image: gitlab-registry.cern.ch/scouting-demonstrator/scouting-docker-images/scdaq-builder:1.0.5
 
 check_formatting:
   stage: check