Prohibit nested intersection types in return position

#KT-11490 Fixed

compiler/testData/diagnostics/tests/implicitNestedIntersection.kt

@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface In<in E>
+open class A : In<A>
+open class B : In<B>
+
+fun <T> select(x: T, y: T) = x
+
+fun <!IMPLICIT_INTERSECTION_TYPE!>foo2<!>() = select(A(), B()) // Type is In<A & B> is prohibited in return position

compiler/testData/diagnostics/tests/implicitNestedIntersection.txt

@@ -0,0 +1,24 @@
+package
+
+public fun foo2(): In<{A & B}>
+public fun </*0*/ T> select(/*0*/ x: T, /*1*/ y: T): T
+
+public open class A : In<A> {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class B : In<B> {
+    public constructor B()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface In</*0*/ in E> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}