Implement Signed PMs

[Peashooter101]

Problem

Found While: Code Reviewing
Found By: @RhythmicSys
Developer: @Peashooter101

SimplePMs are unsigned and does not support native Minecraft chat signing, removing the base-game's implemented chat features.

Users should be able to report players who violate Minecraft TOS and Community Guidelines like they can for public chats.

Original Code Review Comment

I would like to see about hooking into the normal /msg handler/event, possibly mapping /reply onto the normal message command and supplying a user as it's functionality (so /reply would basically call /msg (user)) - main reason for wanting this is that minecraft /msgs are signed where currently, simplePMs just is server-sided messages, so they can't be reported if something is happening in PMs

Originally posted by @RhythmicSys in #8 (comment)