Add clazy as a CMake mechanism to perform static-analysis

The clazy-standalone is used.
By default it runs using checks of level0

To change the behaviour define the environment variable
   CLAZY_CHECKS=level0,level1,level2
for instance, this will use also checks of level1 and level2.

Beware that more than level0 may be false positives.

Refer to clazy documentation for more details.