qmllsutils: Extend resolveNameInQmlScope and return QQmlLSUtilsExpressionType

In qmllsutils.cpp we have too many helper functions doing the similar job, resolving the given name in the scope and returns QQmlLSUtilsExpressionType.

The most mature one resolveNameInQmlScope that is currently returning SignalOrProperty type. We should aim for unifying type/name resolvers in this function and return QQmlLSUtilsExpressionType.

Also, delete SignalOrProperty type and use QQmlLSUtilsExpressionType instead.