Create ASP.NET Core Aurelia Template for dotnet new

**I'm submitting a feature request**

Create ASP.NET Core Aurelia Template for dotnet new in favour of the Aurelia CLI generated dotnet template.

The ASP.NET Core Aurelia Template was retired in dotnet v2.0.
currently, out of the box, `dotnet new` no longer provides an Aurelia template.

This issue has been created to continue the discussion which was born out of this issue: https://github.com/aurelia/cli/issues/979

Which resulted in the intention to create a custom dotnet new template for Aurelia:
https://docs.microsoft.com/en-us/dotnet/core/tools/custom-templates

**Current behavior:**
The Aurelia CLI creates an outdated ASP.NET Core template.

* **What is the expected behavior?**
There needs to be an up to date ASP.NET Core template available for Aurelia as is the case for other SPA frameworks. The template should contain some basic code demonstrating the use of the framework with ASP.NET Core as is the case for the other SPA frameworks.

* **What is the motivation / use case for changing the behavior?**
Help Aurelia gain traction as a front-end framework in the huge .NET developer community.