create new @embroider/reverse-exports package

[lolmaus]

Some references:

• https://nodejs.org/api/packages.html#package-entry-points
• https://webpack.js.org/guides/package-exports/

[mansona]

Looking good so far 🎉 we need to add the conditional exports stuff (at least for import, export, and default) and then "just" add the implementation 😂

[mansona]

as for the case where we have an exports but don't match it correctly, I think we should throw with an error like:

You tried to reverse exports for the file <filename> in package <package name> but it does not match any of the packages exports rules. This means it should not be possible to access directly.

[lolmaus]

as for the case where we have an exports but don't match it correctly, I think we should throw with an error like:

Done.

[mansona]

Looks good 🎉