Example for starting a gRPC server with picocli

[tisonkun]

Hi @remkop!

I have a new idea to create a gRPC server launch based on picocli - https://github.com/tisonkun/morax/issues/25

The main responsibility should be:

• pass over CLI options
• the main runnable/callable method to start the server and run forever until signals

I wonder if there is some sample projects already doing so and thus I can take a look.

I know that spring-maven-plugin's script has some lines to handle start/stop a spring boot application, but my gRPC server is barely built.