feat: expose chain-registry structs (backport #4472)

[mergify]

This PR exposes the chain registry structs that were recently added.
This package will then be used by Ignite Connect app to avoid duplication (ignite/apps#102)

---

This is an automatic backport of pull request #4472 done by Mergify.

[mergify]

Cherry-pick of ec26e2e has failed:

On branch mergify/bp/release/v28.x.y/pr-4472
Your branch is up to date with 'origin/release/v28.x.y'.

You are currently cherry-picking commit ec26e2ee.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   ignite/pkg/chainregistry/asset.go
	new file:   ignite/pkg/chainregistry/chain.go
	new file:   ignite/pkg/chainregistry/consts.go
	new file:   ignite/pkg/chainregistry/doc.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   ignite/services/scaffolder/chain_registry.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally