This changes our code to use the RTM version of the framework reference
assemblies rather than preview.

The RTM version though forces a reference to Microsoft.VisualBasic.dll
when building VB projects. That caused a compilation error in part of
our code because of the following pattern

```vb
For Each str in strings
```

In VB the identifier in the `For Each` is not necessarily a new
declaration but can also refer to existing identifiers. Hence this name
must go through standard name lookup.

Once the reference to Microsoft.VisualBasic.dll is added the
`Microsoft.VisualBasic.Conversions` module becomes available and the
method `Str` in that module is now a valid top level name. This causes
the above code to stop compiling. Fix is to use a non-conflicting
identifier.

closes #517711