scaladoc: clauses with evidence parameters as context bounds

[Gedochao]

This needs a change in scaladoc to recognize using clauses with evidence parameters as context bounds. Right now it seems the logic is that a context bound is recognized only if the evidence parameter is an implicit.

@Florian3k can you take this on? Alternatively, who else is working on scaladoc these days?

Originally posted by @odersky in #21257 (comment)

Related:

• Switch mapping of context bounds to using clauses in 3.6 #21257
• Change rules for given prioritization #19300