[FIR] Prefer the non-smartcasted receiver in resolution if it's visible

Previously, we would ignore the candidate with the non-smartcasted
receiver if they have the same symbol.
Now we prefer them when they're visible or when the smart cast changes
the nullability.

compiler/testData/codegen/bytecodeText/falseSmartCast.kt

@@ -1,5 +1,3 @@
-// IGNORE_BACKEND_K2: JVM_IR
-
 open class SuperFoo {
     public fun bar() {
         if (this is Foo) {