Fix VerifyError on primitive override properties

Don't just blindly map property type in PropertyCodegen when generating getter:
we already have its full signature, so we can just as well take the type from
it. The former also isn't correct for properties which are overrides with a
primitive type. Simple mapType is safe for setter though, because the type of a
method parameter cannot change with override on JVM

The change in StackValue relates to call sites of properties which return Unit:
in that case StackValue's this.type is V, whereas the return type of its getter
is Ljet/Unit; -- so coerceTo was coercing from the wrong type in case of getter
calls

 #KT-4373 Fixed
 #KT-4383 Fixed

compiler/testData/codegen/box/properties/primitiveOverrideDefaultAccessor.kt

@@ -0,0 +1,11 @@
+trait R<in T: Comparable<T>> {
+    var value: T
+}
+
+class A(override var value: Int): R<Int>
+
+fun box(): String {
+    val a = A(239)
+    a.value = 42
+    return if (a.value == 42) "OK" else "Fail 1"
+}