CMake: Change logic for default install location
CMake: Change logic for default install location

Change default installation logic in top-level CMakeLists.txt so that
the installation directory not dependent on the value of
CMAKE_Fortran_MODULE_DIRECTORY. The default location will be configured
correctly even if the user does not name the build directory "build" but
instead chooses some other name for the build directory.

OpenFAST/OpenFAST,OpenFAST/OpenFAST,OpenFAST/OpenFAST