Component serialization doesn't match vanilla

[Kebab11noel]

Some components when serialized doesn't match vanilla's string represantation which causes issues with server side signature validation. Example of a difference:
Adventure:

{"extra":[{"color":"#ff00ff","text":"PREPEND\u003e"},{"text":"/sign test"},{"color":"#ff00ff","text":"\u003cAPPEND"}],"text":""}

Minecraft:

{"extra":[{"color":"#FF00FF","text":"PREPEND>"},{"text":"/sign test"},{"color":"#FF00FF","text":"<APPEND"}],"text":""}