[MacSDK] Add F# targets to VisualStudio/v17.0 directory (#21218)
.NET 6 RC 2 adds an MSBuild check to see that the VisualStudioVersion
property is below 17.0 and reports a not supported warning if this is
the case. Updating the VisualStudioVersion to 17.0 used in Visual
Studio for Mac 17.0 to fix this warning breaks F# SDK projects and
classic F# projects since Mono's MSBuild tries to load F# targets
files from a directory which does not exist:
xbuild/Microsoft/VisualStudio/v17.0/FSharp
Adding a v17.0 directory to Mono allows Visual Studio for Mac 17.0
to define VisualStudioVersion to be 17.0 and restore and build F#
projects.