bug(windows): Label tracks do not accept input from Keyman Desktop in Audacity 2.1.2 and later

[Initial report on community.software.sil.org](https://community.software.sil.org/t/keyman-win10-no-longer-recognized-by-newer-audacity-versions/536).

Recent versions of Audacity, from 2.1.2 onward, appear to bypass Keyman entirely for input. Looking at the [Audacity 2.1.2 release notes](https://github.com/audacity/audacity/releases/tag/Audacity-2.1.2), the major change made was an update to [wxWidgets](https://www.wxwidgets.org/) 3.0.2.

So I suspect that we should be looking at wxWidgets 3.0 for this compat issues. In 3.0.0 they merged ANSI and Unicode support and my stab-in-the-dark guess is that they may have inadvertently turned their windows into ANSI windows in the process. Or something like that, I hope, which could be easy to resolve.