fix: review the pub types/fields(post-split)(1)

[duguorong009]

Description

• review & correct the pub types/fields in every crate

Related issues

• Resolve [post frontend-backend split] Review pub types / fields #259

Changes

• add (crate) limit to needed types/fields in every crate
• remove the unused methods
• add #[allow(dead_code)] for only necessary case, like Debug-derived structs(PinnedVerificationKey, ...)

[ed255]

In general I think there should be no #[allow(dead_code)] anywhere, because it's only needed for non-pub entries, but if they're not public and they're not used anywhere, why keep them?

[ed255]

I think it's inconsistent that Region is not pub but it has pub methods.

[duguorong009]

Remove the mehods in 82ff602

[davidnevadoc]

I agree with @ed255, we shouldn't have #[allow(dead_code)], these functions should be removed or remain pub.
The purpose of this PR is to restore function visibility to the state be fore the front/back split right? ( I assume that during the process, the visibility for many function was increased for convenience.)
If this is the case, I suggest we leave thing as pub when in doubt.

[duguorong009]

Thanks for the detailed review! @ed255 @davidnevadoc

I followed the suggestions - roll back some pub & remove the unused methods.
Pls re-check the PR.

[ed255]

LGTM!