CMake option to turn off driver builds

[andrew-platt]

Is your feature request related to a problem? Please describe.
When OpenFAST is built through SPACK in ExaWind, all the driver code is build with it. For this use case, these driver codes are not needed.

Describe the solution you'd like

• CMakeLists.txt - option(BUILD_DRIVERS "Build driver codes" on)
• Add logic to turn off driver building in relevant cmake files
• Add logic to testing for driver building

This idea came from a comment by @jrood-nrel about the OpenFAST build times while presenting ExaWind in a seminar.