`dotnetup install` doesn't work with an `--install-path` set to a relative directory

[baronfel]

Describe the bug

I'm working on samples using dotnetup, but when I use a relative path for --install-root the command doesn't actually seem to create the destination directory.

When I move to a fully-qualified path the directory contents appear correct.

[baronfel]

This seems to be fixed as one of the changes in #53464