Move OverridingUtil#getUpperBound to OverloadUtil, add tests on overloads

compiler/testData/diagnostics/tests/redeclarations/typeParameterWithTwoBounds.kt

@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo
+interface Bar
+
+<!CONFLICTING_JVM_DECLARATIONS!>fun <T> foo(x: T): T<!> where T: Foo, T: Bar {null!!}
+<!CONFLICTING_JVM_DECLARATIONS!>fun foo(x: Foo): Foo<!> {null!!}
+fun foo(x: Bar): Bar {null!!}

compiler/testData/diagnostics/tests/redeclarations/typeParameterWithTwoBounds.txt

@@ -0,0 +1,17 @@
+package
+
+public fun foo(/*0*/ x: Bar): Bar
+public fun foo(/*0*/ x: Foo): Foo
+public fun </*0*/ T : Foo> foo(/*0*/ x: T): T where T : Bar
+
+public interface Bar {
+    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 Foo {
+    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
+}