Fix BookHack

[MasterDash5]

This resolves an issue where players can sign a book with JSON formatted components in the pages. Some modded clients abuse this to create books that contain a clickEvent to trick an admin to run a command.

This PR strips the pages of components when books are signed.

[hpfxd]

I think this should be behind a config option.

Also, it's possible to color books in Vanilla 1.8 by pasting the special § character. I'm unsure if that's converted into components before being sent to the server, but if that's the case, I think this should be disabled by default to not interfere with that mechanic.

[MasterDash5]

This doesn't affect pasting the § character in the book. This is just for JSON components, which can only be sent by a modded client. It's also worth noting 1.12 and newer have this same fix, so I don't see much benefit in turning this behavior off.