Add an ignores API

[Mm2PL]

Checklist

• I'm reporting a problem with Chatterino
• I've verified that I'm running the most recent nightly build or stable release
• I've looked for my problem on the wiki
• I've searched the issues and pull requests for similar looking reports

Describe your issue

Chatterino's ignore system isn't scriptable at all.

I don't have a concrete idea on how this should look but I'd say Lua should somehow receive an event when Chatterino checks for ignores and Lua should either return a new message or block it. Maybe even the same system as #4619

Screenshots

N/A

OS and Chatterino Version

Chatterino 2.4.3 DEBUG (commit 1f0aa80 modified) built with Qt 5.15.9 Running on Arch Linux, kernel: 6.3.1-arch1-1