[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

compiler/testData/diagnostics/tests/redeclarations/EnumName.kt

@@ -1,3 +1,5 @@
 enum class A {
-    <!REDECLARATION!>name<!>
+    <!REDECLARATION!>name<!>,
+    <!REDECLARATION!>ordinal<!>,
+    <!DEPRECATED_DECLARATION_OF_ENUM_ENTRY!>entries,<!>
 }