[FIR] Check conflicting overloads via scopes

Scopes may return private symbols from
supertypes, they should not clash with
symbols from the current class.

For example, see:
`FirLightTreeBlackBoxCodegenWithIrFakeOverrideGeneratorTestGenerated.FakeOverride#testPrivateFakeOverrides1`

Lombok shouldn't generate functions if the
user has defined explicit ones.

In K1 generated functions are not really
added to the declared members scope.

^KT-61243 Fixed

plugins/lombok/testData/diagnostics/clashAccessors.kt

@@ -39,6 +39,11 @@ public class ClashTest extends SuperClass {
         return human;
     }
 
+    private int score;
+
+    public void setScore(int score, int times) {
+
+    }
 
     static void test() {
         val obj = new ClashTest();
@@ -88,6 +93,9 @@ fun test() {
     <!VAL_REASSIGNMENT!>obj.age<!> = 12
     val age = obj.age
 
+    obj.setScore(41)
+    obj.score = 12
+
 
     obj.getName()
     obj.setName("Al")