cmd: add the possibility to unlinks the core lightning form coffee

[vincenzopalazzo]

We have a coffee setup command, but we do not have and unlink command, so we should add it to make it easy.

coffee unlink <cln root path>, and then maybe we can rename the coffee setup to coffee link?

What do you think @tareknaser ?

[tareknaser]

Maybe we can have:

• coffee setup and coffee teardown
  or
• coffee activate and coffee deactivate

[tareknaser]

I gave this a try, but it looks like we need to wait for laanwj/cln4rust#131 before testing. Here is the commit: 862a9eb

[vincenzopalazzo]

No better, link and unlink

You are not activating anything, but you are linking the core lightning configuration to the coffee configuration.

In Linux terms, this is a link operation https://linuxize.com/post/how-to-create-symbolic-links-in-linux-using-the-ln-command/