Fix variances for wildcard arguments in TypeMaps and TypeAccumulators
Fix variances for wildcard arguments in TypeMaps and TypeAccumulators

Parameter variance is only taken into account for concrete arguments,
should be ignored for wildcards. Test case is ../pos/pos_valueclasses/t7818.scala.

sjrd/dotty,som-snytt/dotty,lampepfl/dotty,dotty-staging/dotty,sjrd/dotty,dotty-staging/dotty,dotty-staging/dotty,som-snytt/dotty,lampepfl/dotty,sjrd/dotty,lampepfl/dotty,som-snytt/dotty,dotty-staging/dotty,sjrd/dotty,sjrd/dotty,lampepfl/dotty,lampepfl/dotty,som-snytt/dotty,som-snytt/dotty,dotty-staging/dotty