Support for `args`

[fdohrendorfG]

Hello,

I would like to add command line argument support. So that those are forwarded to the apphost project.

We use this to have different configurations in our apphost project.

Example:

// Spin up Sql Server as a container
var useSqlServerContainer = args.Contains("--use-sql-server-container");

Would you accept a PR for this?

Best, Florian