Describe the feature

Hi there!

First, I wanted to say thanks for your work on these packages - they are all very useful!

I'm currently developing a ASP.NET Core project template and your Boxed.DotnetNewTest package is incredible helpful and a real time saver, compared to manually installing my template over and over again ^^

During development, I sometimes run into problems because the dotnet cli seems to use a stale version of my template; i.e., I change the available symbols in my template.json, but the changes are not picked up on the next run of my unit test.

Uninstalling the template between test runs reliable fixes these problems.

I therefore propose to add a new DotnetNew.UninstallAsync method (similar to the existing DotnewNew.InstallAsync method) to enable users of the library to programmatically uninstall project templates.

I already prepared the necessary changes to the library in a local branch - I would be very happy to open a PR with my changes, if you agree that it would be a useful addition to your library.

Thanks!