[IR] Properly serialize IrDeclarationOrigin.GeneratedByPlugin to klibs

^KT-56911 Fixed

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/BridgesBuilding.kt

@@ -234,8 +234,11 @@ internal class BridgesBuilding(val context: Context) : ClassLoweringPass {
 }
 
 internal class DECLARATION_ORIGIN_BRIDGE_METHOD(val bridgeTarget: IrFunction) : IrDeclarationOrigin {
+    override val name: String
+        get() = "BRIDGE_METHOD"
+
     override fun toString(): String {
-        return "BRIDGE_METHOD(target=${bridgeTarget.symbol})"
+        return "$name(target=${bridgeTarget.symbol})"
     }
 }