19106: core/lib: Add macros/utils.h header r=aabadie a=maribu
### Contribution description
The macros CONCAT(), MIN(), and MAX() are defined over and over again in RIOT's code base. This de-duplicates the code by moving the macros to a common place.
### Testing procedure
Generated binaries don't change, as this only a de-duplication of macros that doesn't change their definition.
### Issues/PRs references
None
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>