Types export from package.json

[chris-cooper]

Description

We have a project that is failing to find TypeScript types when importing from cesium. It works when importing from @cesium/engine, (though that package doesn't have an exports section in the package.json).

This is the error:

Could not find a declaration file for module 'cesium'. '...my_project/node_modules/cesium/index.cjs' implicitly has an 'any' type.
  Try `npm i --save-dev @types/cesium` if it exists or add a new declaration (.d.ts) file containing `declare module 'cesium';`

The change in this PR allows the types to be found.

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with a short summary of my change
• I have added or updated unit tests to ensure consistent code coverage
• I have updated the inline documentation, and included code examples where relevant
• I have performed a self-review of my code

[github-actions]

Thank you for the pull request, @chris-cooper!

✅ We can confirm we have a CLA on file for you.

[ggetz]

Thanks @chris-cooper! The change looks good. Could you please update CHANGES.md with a summary of the fix?

[chris-cooper]

Ok thanks @ggetz I've added to CHANGES.md and rebased.

[ggetz]

Great, thanks @chris-cooper!