Add AccountUpdate.approveIf

[rpanic]

Implement a function conditionally attaching a child account update.
AccountUpdate.approveIf(child: AccountUpdate, condition: Bool)

[Trivo25]

What about this?

 /**
   * Create an account update that is added to the transaction only if a condition is met.
   *
   * See {@link AccountUpdate.create} for more information. In this method, you can pass in
   * a condition that determines whether the account update should be added to the transaction.
   */
  static createIf(condition: Bool, publicKey: PublicKey, tokenId?: Field) {