cmake-gui: structured CMAKE_GENERATOR_TOOLSET selection
!2832 (merged) resolved #17343 (closed) by adding a drop-down to select
CMAKE_GENERATOR_PLATFORM. It would be nice to offer something similar to extend the free-form text field we already have for
CMAKE_GENERATOR_TOOLSET. The toolset case is a bit more complicated because the field supports a
,-separated list of settings. Also the set of available toolsets may be hard to find.