FIO-7733: remove stale types

[brendanbond]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-7733

Description

Previously, the package.json file in this repo was pointing to manually crafted types in the ./types folder. These types are 4 years old and stale. Now that we use Typescript to build the library, we should be using the colocated *.d.ts files in lib, which come for free without the "types" parameter in the package.json

Breaking Changes / Backwards Compatibility

Shouldn't be an issue; in fact, should improve dev ex by using up-to-date type definitions from the build step.

Dependencies

n/a

How has this PR been tested?

n/a

Checklist:

• [x] I have completed the above PR template
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation (if applicable)
• [x] My changes generate no new warnings
• [x] My changes include tests that prove my fix is effective (or that my feature works as intended)
• [x] New and existing unit/integration tests pass locally with my changes
• [x] Any dependent changes have corresponding PRs that are listed above