Fixes serialization/deserialization problems with `null`, arrays and `Date` on websocket messages

[mrctrifork]

Ideally, messages would just be Decoded from Typebox's schema in order to determine whether to keep a date or parse it from a String.

• Adds tests
• Ensures we can parse Date strings
• Ensures we can parse arrays
• Ensures we can parse nested date-strings

closes #85 (should) closes #54 also closes #37

[mrctrifork]

Thank youuu!