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/regressions/kt251.kt

@@ -5,7 +5,7 @@ class A() {
             field = <!TYPE_MISMATCH!>value<!>
         }
     val y: Int
-        get(): <!WRONG_GETTER_RETURN_TYPE!>String<!> = "s"
+        get(): <!WRONG_GETTER_RETURN_TYPE(Int; String)!>String<!> = "s"
     val z: Int
         get() {
             return <!TYPE_MISMATCH!>"s"<!>