Use New 7TV Cosmetics System

[Nerixyz]

Pull request checklist:

• CHANGELOG.md was updated, if applicable

Description

This PR implements the new cosmetics system for 7TV, where cosmetics are updated using the EventAPI. This is essentially the same code that's already in chatterino7 (relevant PR). Adding and updating a badge for a user only requires taking one lock.

Once this is merged, I'm planning to add support for the similar BTTV system as well.

[Nerixyz]

--- /dev/fd/63	2023-04-04 14:15:21.963666976 +0000
+++ /dev/fd/62	2023-04-04 14:15:21.963666976 +0000
@@ -1264,8 +1264,8 @@
     this->threads_[thread->rootId()] = thread;
 }
 
-const std::unordered_map<QString, std::weak_ptr<MessageThread>> &
-    TwitchChannel::threads() const
+const std::unordered_map<QString, std::weak_ptr<MessageThread>>
+    &TwitchChannel::threads() const
 {
     return this->threads_;
 }
src/providers/twitch/TwitchChannel.cpp differs!!!!!!!
At least one file is poorly formatted - check the output above

clang-format should be updated :)

[github-actions]

clang-tidy made some suggestions

[github-actions]

clang-tidy made some suggestions

[pajlada]

I'm happy to merge this in when the network issue thing is resolved

[pajlada]

Thank you for putting in the effort!