VS: Add option to select the version of the toolset used
- Adds support for a new parameter 'version' in the toolset setting to select the version
- Adds a new cmake variable CMAKE_VS_PLATFORM_TOOLSET_VERSION which holds the version, if one is set (blank indicates default)
The usage is as indicated in the feature request. In order to select a specific compiler version, the toolset must be specified with alongside with the specific version: -T v141,version=14.11
Fixes: #17549 (closed)
Topic-rename: vs-toolset-version