[ConstraintSystem] Rework handling of object literal expressions

Instead of special casing argument-to-parameter matching for
object literal expressions, let's allow constraint system to
lookup a witness initializer and apply it to the given set
of arguments.

This also simplifies constraint application because
`coerceCallArguments` could be used to form type-checked
argument expression.

lib/Sema/CSSimplify.cpp

@@ -6754,7 +6754,7 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyMemberConstraint(
       return SolutionKind::Solved;
     } else if ((kind == ConstraintKind::ValueMember ||
                 kind == ConstraintKind::ValueWitness) &&
-               baseObjTy->isHole()) {
+               baseObjTy->getMetatypeInstanceType()->isHole()) {
       // If base type is a "hole" there is no reason to record any
       // more "member not found" fixes for chained member references.
       markMemberTypeAsPotentialHole(memberTy);