Add unit tests for LoginMessage class

[coderabbitai]

The LoginMessage class in the packages/mcots/payloads/LoginMessage.ts file is not covered by tests. Adding unit tests for this class is crucial for ensuring its reliability and maintainability.\n\nPR URL: https://github.com/rustymotors/server/pull/2037\nComment URL: https://github.com/rustymotors/server/pull/2037#discussion_r1724152048\n\nPlease add unit tests to cover all functionalities of the LoginMessage class.