[Tests] Add test for KT-59493

This is to record the red->green change in behavior between K1 and K2,
when K2 correctly handles resolution/inference of an extension function
with definitely non-nullable type.

compiler/testData/diagnostics/tests/explicitDefinitelyNotNullableViaIntersection/kt59493.fir.kt

@@ -0,0 +1,37 @@
+// !LANGUAGE: +DefinitelyNonNullableTypes
+
+import kotlin.reflect.KProperty1
+
+class Mem
+class Ext
+
+class Foo<T> {
+    fun foo(prop: KProperty1<T & Any, *>): Mem = Mem()
+}
+fun <T> Foo<T>.bar(prop: KProperty1<T & Any, *>): Ext = Ext()
+
+class Bar<T> {
+    fun bar(prop: KProperty1<T & Any, *>): Mem = Mem()
+}
+fun <T> Bar<T>.bar(prop: KProperty1<T & Any, *>): Ext = Ext()
+
+class Baz<T> {
+    fun baz(prop: KProperty1<T, *>): Mem = Mem()
+}
+fun <T> Baz<T>.baz(prop: KProperty1<T & Any, *>): Ext = Ext()
+
+fun <T> id(t: T): T = t
+
+fun main() {
+    val r01: Mem = Foo<String?>().foo(String::length)
+    val r02: Mem = Foo<String?>().foo(id(String::length))
+
+    val r03: Ext = Foo<String?>().bar(String::length)
+    val r04: Ext = Foo<String?>().bar(id(String::length))
+
+    val r05: Mem = Bar<String?>().bar(String::length)
+    val r06: Mem = Bar<String?>().bar(id(String::length))
+
+    val r07 = <!DEBUG_INFO_EXPRESSION_TYPE("Ext")!>Baz<String?>().baz(String::length)<!>
+    val r08: Ext = Baz<String?>().baz(id(String::length))
+}

compiler/testData/diagnostics/tests/explicitDefinitelyNotNullableViaIntersection/kt59493.kt

@@ -0,0 +1,37 @@
+// !LANGUAGE: +DefinitelyNonNullableTypes
+
+import kotlin.reflect.KProperty1
+
+class Mem
+class Ext
+
+class Foo<T> {
+    fun foo(prop: KProperty1<T & Any, *>): Mem = Mem()
+}
+fun <T> Foo<T>.bar(prop: KProperty1<T & Any, *>): Ext = Ext()
+
+class Bar<T> {
+    fun bar(prop: KProperty1<T & Any, *>): Mem = Mem()
+}
+fun <T> Bar<T>.<!EXTENSION_SHADOWED_BY_MEMBER!>bar<!>(prop: KProperty1<T & Any, *>): Ext = Ext()
+
+class Baz<T> {
+    fun baz(prop: KProperty1<T, *>): Mem = Mem()
+}
+fun <T> Baz<T>.baz(prop: KProperty1<T & Any, *>): Ext = Ext()
+
+fun <T> id(t: T): T = t
+
+fun main() {
+    val r01: Mem = Foo<String?>().foo(String::length)
+    val r02: Mem = Foo<String?>().foo(id(String::length))
+
+    val r03: Ext = Foo<String?>().bar(<!TYPE_MISMATCH!>String::length<!>)
+    val r04: Ext = Foo<String?>().bar(id(String::length))
+
+    val r05: Mem = Bar<String?>().bar(String::length)
+    val r06: Mem = Bar<String?>().bar(id(String::length))
+
+    val r07 = <!DEBUG_INFO_EXPRESSION_TYPE("Mem")!>Baz<String?>().baz(<!TYPE_MISMATCH!>String::length<!>)<!>
+    val r08: Ext = Baz<String?>().baz(id(String::length))
+}