This commit adds GRCC into the CMake build system and creates the
executables from the .grc files on demand.
Because there is always the case that the gr-satnogs has not
been installed yet in the system, we still ship the auto-generated
from our side executables. In next releases, during the install
target, the GRCC and the executables generation, will be called
after the gr-satnogs is installed.