Define types for Paragon exports

[adamstankiewicz]

Through https://github.com/openedx/paragon/pull/1962, it was discovered that we need to define types for Paragon's exports defined in src/index.js.

In the short term, we'd like to define these types in the Paragon repository itself.

An example related issue from the perspective of a consumer:

[engineer] who is trying to bring TypeScript into frontend-app-admin-portal ran into issue where TypeScript was complaining that Paragon's Button component didn't have types defined and would need to define them locally in the application to get around it.

[PKulkoRaccoonGang]

Pull Request: https://github.com/openedx/paragon/pull/2177

[monteri]

Reacreated PR: https://github.com/openedx/paragon/pull/2566