[WIP] Port "implicit definition needs explicit type" error to new scheme

[x3ro]

Part of the effort documented in #1589 to port all error messages to
the new scheme.

Marked as WIP because I need some help in coming up with a test case for this part here.

[dottybot]

Hello, and thank you for opening this PR! 🎉

All contributors have signed the CLA, thank you! ❤️

Have an awesome day! ☀️

[x3ro]

@nicolasstucki Are you able to suggest someone who could help me figure out the missing test case 🤔

[nicolasstucki]

I can have a look at it. Could you rebase it.

[anatoliykmetyuk]

Thanks for working on this @x3ro!

Marked as WIP because I need some help in coming up with a test case for this part here.

The following two negative tests take that branch:

https://github.com/lampepfl/dotty/blob/4d3f315a6f7804f2a441497e0b2060fba8e5928d/tests/neg/i3067.scala
https://github.com/lampepfl/dotty/blob/4d3f315a6f7804f2a441497e0b2060fba8e5928d/tests/neg/i3067b.scala

So basically make an implicit object extend a type with generic parameters while not fully specifying these generic parameters.

Looks good to me – we can merge it after it is rebased on master and the missing test added.

[anatoliykmetyuk]

I'm closing this one since there was no activity on it for a couple of months – feel free to reopen it if any further progress happens.