Verify our exports with arethetypeswrong

[timostamm]

https://github.com/arethetypeswrong/arethetypeswrong.github.io has been available as a CLI for some time.

Same as bufbuild/protobuf-es#456, we should use it to verify our exports. We need to pick up the work started in bufbuild/protobuf-es#536.

We still populate the main property in our package.json files, which is necessary for Webpack < 5.x (see #167). We should verify whether it is still necessary.

[srikrsna-buf]

I tried to do this for knit. The latest unreleased version passes the online test without any problems. It also has sub exports similar to the connect package. Could be useful to take a look.

[timostamm]

I tried to do this for knit. The latest unreleased version passes the online test without any problems. It also has sub exports similar to the connect package.

Yes, it's not a big lift to fix reported issues, but I think it's important to understand any issues we fix and nail down a pattern for exports that we can apply to all repositories. The attw CLI then allows us to guard against regressions in CI - but that's only helpful if we have confidence in what issues attw detects and to which ones it is blind.

[smaye81]

Fixed by #838