Build type enhancement properly, by taking into account both bounds of the original flexible type

^KT-44420 Fixed

compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/buildFlexibleEnhancement.kt

@@ -0,0 +1,35 @@
+// FIR_IDENTICAL
+// FULL_JDK
+// WITH_RUNTIME
+// WITH_REFLECT
+
+// FILE: NonNullApi.java
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.TYPE, ElementType.PACKAGE})
+@javax.annotation.Nonnull
+@javax.annotation.meta.TypeQualifierDefault({ElementType.METHOD, ElementType.PARAMETER})
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+public @interface NonNullApi { }
+
+// FILE: Foo.java
+
+import java.util.Collection;
+
+@NonNullApi
+public class Foo<E> {
+    public Foo(Collection<? extends E> c) {}
+}
+
+// FILE: main.kt
+
+fun test() {
+    val collection: Collection<Int> = listOf(1, 2, 3)
+    Foo(collection)
+}