[Ethers-v5] Export types

[krzkaczor]

Closes: #278

[krzkaczor]

@zemse can you test in on your codebase before I release? I will mark it as major update since formatting WILL change (breaking changes in prettier). I think it's the only sane thing to do...

[zemse]

I used this on the code base, it works fine including the exporting types from index.ts.

I think it can be worth mentioning that projects that use this new version need typescript>=3.8. New projects would have that but old projects will need to upgrade their typescript.

[krzkaczor]

@zemse thanks for testing! I added some more fixes and gonna release it in a sec.