We have apparently been sorting everything by switch-in order this
entire time, not just move redirection. This appears to be a mistake
in #5216
The actual bug fix is just the single line in `comparePriority`,
everything else is just documentation, and a bit of optimization of
how speed ties are resolved.
Fixes#6319
In Generation 8, a Pokemon's speed updates dynamically. Meaning that it can move sooner than expected if its speed is modified by something such as tailwind or swift swim. This is different from past generations where the Pokemon's updated speed would only take effect the next turn.