Don't discriminate generics during callable references resolution

^KT-49038 Fixed

compiler/testData/diagnostics/tests/callableReference/kt49038.kt

@@ -0,0 +1,13 @@
+fun take(arg: Any) {}
+
+fun <T> foo(a: A, t: T) {} // 1
+fun <T> foo(b: B, t : T) {} // 2
+fun foo(i: Int) {} // 3
+
+class A
+class B
+
+fun box(): String {
+    val ref1 = take(::<!CALLABLE_REFERENCE_RESOLUTION_AMBIGUITY!>foo<!>) // error before 1.6.20; ok, resolved to (3) since 1.6.20
+    return "OK"
+}