Change TypeParameter to be a Expression, to support kotlin intersection type

[kunli2]

This change is to support Kotlin intersection type like this

              import java.util.*

              @Suppress("UNUSED_PARAMETER")
              fun <T : Any?> test(n: Optional <  T   &    Any > = Optional.empty<T>()) {}

Optional < T & Any > is a J.ParameterizedType,
If we parse T & Any as a J.TypeParameter, then it needs to be a J.Expression since J.ParameterizedType requires a JContainer<Expression> for type parameters.

There is an alternative way to avoid this change, which is to parse T & Any to a K.Binary with a new binary type.

[knutwannheden]

I think we should first finish and integrate #3652 which will introduce J.IntersectionType.

[kunli2]

yes, let's use J.IntersectionType instead.