"caddy add-package", "caddy remove-package" could be idempotent

[gedw99]

For idempotency, it would be useful if caddy add-package and caddy remove-package could be idempotent.

caddy remove-package, will return "Error: package is not added" if I do it twice.

caddy add-package, will return "Error: package is already added", if I do it twice.

This idempotency is a nice thing in any architecture, when managing a fleet and building a fleet, because you can just store the package list somewhere and then do add-package without worrying if it was done in the past. Treat them like Cows, not delicate kittens :)

what is the best way to handle this ?

```caddy add-package github.com/x/y```, will return "Warn: package github.com/x/y is already added",

[mholt]

I guess that makes sense. Want to submit a PR?

[gedw99]

Hey @mholt

Can you also comment on #6549, since it's related.

Might have some bearing on this PR. I would like to get this as tight as possible since it is SBOM related.

[mholt]

I think we should just stick to idempotency for now. As mentioned in other issues, build automation with these commands isn't really intended (there are better tools for the job like xcaddy).

[gedw99]

Got it . Thanks @mholt for steering me .