[ts] Imports cannot be found with '.js' extension

[maxburke]

In upgrading to flatc-22.9.29 one thing we've noticed is that change 4fca4dc adds a .js extension to imports in generated code, but it's causing build errors for us:

    Cannot find module './binary-query-element.js' from 'src/generated/query-element-union.ts'

Does the extension need to be specified? It worked previously when no extension was specified.

If the extension does need to be specified, why is it .js instead of the .ts the file-on-disk has?

[maxburke]

Duplicate of #7661, closing