[NI] Properly support UnsafeVariance annotation

#KT-38134 Fixed
 #KT-34433 Fixed
 #KT-31823 Fixed

compiler/testData/codegen/box/inference/unsafeVarianceCodegen.kt

@@ -0,0 +1,11 @@
+class A<out K> {
+    fun foo(x: @UnsafeVariance K): K = x
+}
+
+fun test(a: A<*>): Any? {
+    return a.foo("OK")
+}
+
+fun box(): String {
+    return test(A<String>()) as String
+}