This corrects the path to `Terminal.Core.Unit.Tests.dll` in the `runut`
unit test script and makes the `runft` feature test script capable of
working with _Release_ builds as well as _Debug_ builds.
The path to `Terminal.Core.Unit.Tests.dll` changed when the project was
restructured, and the `runut` script was never updated to reflect that
change. That has now been corrected.
And the `runft` script used to be hard coded to look for tests in the
_Debug_ directory, but it has now been updated to use the
`%_LAST_BUILD_CONF%` environment variable, so it should work for both
_Debug_ and _Release_ builds.
## Validation Steps Performed
I've manually confirmed that the `runut` and `runft` scripts now work as
expected.
Closes#8485
