Add Q# with C# host program template

[dime10]

Is your feature request related to a problem? Please describe.
Currently need to generate the Q# library and host program separately, from the command line, and then add the library to the host program. This is less convenient than selecting a single template from the command palette in VS Code.

Describe the solution you'd like
Adding a new template to the VS Code extension (and/or others) that directly creates a Q# library together with the pre-configured C# host program via the command palette. Optionally for other host languages too.

Describe alternatives you've considered
Just a convenience feature.

Additional context

[bettinaheim]

@riccardo: We have a feature request for the extensions - could you please make sure this gets triaged?