- Don't treat givens as higher priority than implicits. The previous logic was faulty anyway.
 - Drop special handling of NotGiven in prioritization. The previous logic pretended to do so,
   but was ineffective.
 - Don't use old priority in general for implicit/implicit pairs. This would make upgrading to givens a constant
   struggle. But do use it as a tie breaker in the case of ambiguities.
 - Also use owner score as a tie breaker if after all other tests we still have an ambiguity.

Previously warnings were produced but not shown since at the same position we already have an ambiguity
error. We now add the note to the error message.

Co-authored-by: Eugene Flesselle <[email protected]>

…ents

This makes slick-migration-api-example work and makes the original scala-uri.scala fail.
See the comment in neg/scala-uri.scala for why this is so. It also needs a change in the
givens in dotty.tools.reporting.Formatting.

The motivation for honoring owner score over the others is that it is often used for explicit
prioritization, so we should take it into account more than other secondary criteria.