[wasm] Add a stub for bundleIdentifier property

Author: kateinoigakukun

Sources/Foundation/Bundle.swift

@@ -440,6 +440,7 @@ open class Bundle: NSObject {
 
 open class Bundle {
     public let bundlePath: String
+    public var bundleIdentifier: String? { return nil }
 
     public static let main = Bundle(path: "")!