Disallow JSR dependency importing itself in deno publish --dry-run

[dsherret]

It will not work when published to JSR. Also, it would cause things to resolve more slowly, the package to list itself as a dependency for the npm compat layer, and potentially cause a duplicate package to be resolved instead since the specifiers would be going through package resolution.

Ref #25191

[lucacasonato]

I think it is useful to be able to import yourself in some cases - for example in doc comments. std does this. So this shouldn't be a blanket ban on self imports in deno_graph, but rather a ban of self imports in files referenced from entrypoints?

[dsherret]

I think it's fine for doc comments.

but rather a ban of self imports in files referenced from entrypoints?

Yeah that makes sense.