[FIR2IR] Fix cast insertion for SAM conversion

The rule is: no cast is required iff the argument type is a
non-reflection function type and a subtype of the expected
function type.
We approximate the cone types using the FIR2IR specific config
to account for intersection types, captured types, etc.

#KT-63345 Fixed
#KT-63510
#KT-62865

compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.kt.txt

@@ -96,3 +96,14 @@ fun test8(a: Function0<Unit>) {
 fun test9() {
   run1(r = ::test9 /*-> KRunnable */)
 }
+
+fun test10(a: Any) {
+  when {
+    when {
+      a is Unrelated -> a is Function0<Unit>
+      else -> false
+    } -> { // BLOCK
+      run1(r = a /*as Function0<Unit> */ /*-> KRunnable */)
+    }
+  }
+}