Auto-update a template before using it

[denisbredikhin]

Is your feature request related to a problem? Please describe.

I'm developing and distributing internal templates across our team. My goal is that when someone wants to use my template (with dotnet new or with Visual Studio), he should always use the latest version. It is too easy to forget to run "dotnet new update" periodically.

Describe the solution you'd like.

Add an option (global dotnet? Or to the package?) that every time you run dotnet new xxx, it first checks for the latest version of xxx package and updates it if needed.

Additional context

It looks like #3418 would also solve my problem but in slightly different way: by allowing working with "online" templates without installing them.

I also evaluated other options, like checking the version and warning the user in post-actions, but all these options have drawbacks.