Upgrade swagger 2.0 to openapi 3.0

[fkneeland-figure]

Summary

Openapi 3.0 is the updated version of swagger 2.0. It has several nice features to make api documentation easier so we should investigate how much work it will take to migrate and whether it is possible with cosmos still using swagger 2.0.

Also should take note of: cosmos/cosmos-sdk#7620

Here is an article explaining some of the differences between swagger 2.0 and openapi 3.0: https://medium.com/@tgtshanika/open-api-3-0-vs-swagger-2-0-94a80f121022

Problem Definition

Proposal

Investigate the feasibility of upgrading swagger 2.0 to openapi 3.0 and make the migration if benefitial.

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[SpicyLemon]

This appears to now be a copy of #2063.
Closing this one in favor of that one.