Module scoping in the libraries

[adizere]

Crate

ibc and relayer

Summary

We should consider exporting modules with more restrictive scoping, e.g., pub(crate) instead of pub.

Original discussion

I actually wanted to ask this before, why don't we use the crate scope more often. I believe in this case for example all mods, except application, can be public at crate level.

Originally posted by @ancazamfir in #518 (comment)

I don't thin it matters too much for the relayer-cli crate, but yeah in general it wouldn't hurt either to make more modules crate scoped, to limit the surface area of our libs.

Originally posted by @romac in #518 (comment)

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate milestone (priority) applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[romac]

Let's keep exporting most things publicly until we get a better idea of what is the surface area needed by downstream users of the ibc and ibc-relayer crate.