Managed unit tests fail to run on x64 Release in CI

[jonthysell]

They run fine locally, but in the CI loop they fail with:

ERROR: ImageDirectoryEntryToData failed!

[jonthysell]

Looks like you have to use the *.build.appxrecipe file as the target assembly, and use the pre-installed vstest (16.5, not the 16.6 from the installer)