Make attempts to require() ESM *always* throw error

[cspotcode]

Follow-up to #1031

Node will throw an error if you try to require() an ESM file.
To preserve backwards-compatibility, this error-throwing was enabled conditionally in ts-node's require hook. It would only throw if you had opted-in to the ESM loader.

https://github.com/TypeStrong/ts-node/pull/1031/files#diff-a2a171449d862fe29692ce031981047d7ab755ae7f84c707aef80701b3ea0c80R880

However, node behavior for .js files is to always throw, and we need to match that. So as a breaking change, we should do the same.