Support uninstalling individual project templates

[S-Luiten]

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.

[Frulfump]

Disabling a template would be nice as well maybe dotnet.config file could be used for this so we could share disablement in the repos themselves.

(not sure if this and the original issue belongs in dotnet/templating instead but that repo sees very little governance from what I can tell)