Support uninstalling individual project templates

### Is your feature request related to a problem? Please describe.
When asking an AI agent to create a new blazor webassembly project, they will most likely use the old wasm template instead of the new blazor web app template. To prevent this, I want to be able to uninstall or at least disable the `blazorwasm` and `blazorwasm-empty` project templates.

### Describe the solution you'd like
`dotnet new uninstall` should be able to uninstall individual project templates by their short name in addition to being able to uninstall project template packages.