Fix "Specify explicit lambda signature" when no parameters exists

So #KT-15075 Fixed

idea/testData/intentions/specifyExplicitLambdaSignature/delegate.kt

@@ -0,0 +1,14 @@
+// IS_APPLICABLE: true
+// SKIP_ERRORS_BEFORE
+// ERROR: Modifier 'override' is not applicable to 'local function'
+// ERROR: Type mismatch: inferred type is () -> Unit but Base was expected
+
+// See also KT-15075
+
+interface Base {
+    fun foo()
+}
+
+class Derived : Base by <caret>{
+    override fun foo() {}
+}