Yellow squiggly lines begone!
Done automatically on .cpp files through `run-clang-tidy`, with manual corrections to the mistakes.
If an import is directly used, but is technically unnecessary since it's recursively imported by something else, it is *not* removed.
The tool doesn't touch .h files, so I did some of them by hand while fixing errors due to old recursive imports.
Not everything is removed, but the cleanup should be substantial enough.
Because this done on Linux, code that isn't used on it is mostly untouched.
(Hopefully no open PR is depending on these imports...)

SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.

Currently, it is possible for the DiscordHandler thread to be in the
middle of sleeping when Dolphin is closing. This results in a very
noticeable delay of up to 2 seconds that is unacceptable, especially
for people who don't use the Discord integration.

This fixes the issue by making the thread wait on an Event instead
and signalling it when shutting down.

also did these things
fixed crash from joining user that isn't hosting via a direct connection
current game stat can now pass to override the current game in config
uses ip endpoint from dolphin.org