Compute return type for property getters more safely

Do not call `isError()` on property's type right after creation of
PropertyGetterDescriptor because the property has no getter yet (it's created
but not yet stored to the property, that happens a bit later), and `isError()`
leads to computation of the delegate type, which for delegated properties
performs some complex resolution (see `VariableTypeResolver#process`) which
relies on the fact that the property already has a getter.

Since the purpose of the original change (883e2e4d) was to support a quick fix
which would add the type to a property in an expression like "val x get() =
...", check the type (or initializer) presence in the PSI instead, this is
safer and is still suitable for the quick fix.

Also fix arguments to "wrong getter type" diagnostic: previously something
useless like "expected Int, actual Int" was reported

 #KT-11809 Fixed

compiler/testData/diagnostics/tests/delegatedProperty/nonDefaultAccessors.kt

@@ -0,0 +1,12 @@
+// KT-11809 Assertion error when delegated property has getter
+
+class A {
+    val p1 by this
+        get
+
+    var p2 by this
+        <!ACCESSOR_FOR_DELEGATED_PROPERTY!>get() = ""<!>
+
+    operator fun getValue(a: Any?, p: Any?) = ""
+    operator fun setValue(a: Any?, p: Any?, v: Any?) {}
+}