Better handle swap immediately?

[wuke32767]

Although #953 looks to be good, but i still noticed somethong:

What if code modders don't use it correctly?

According to https://github.com/EverestAPI/Resources/wiki/Making-Code-Mods#on-hooks, when hooking a coroutine with SwapImmediately, sometimes the method suffix will not run. However, #953 will ALWAYS run them. While nobody should be doing this, this could cause problems in the future:

• B flattens the sequence, just because they can.
• A adds a method suffix.
  • the suffix should not run, but...
• A runs before B.
  • their sequence will be flattened by B. so it runs.
• A is released with the bug.
• Some users don't enable B. For no reason.
• A can't work.

Actually there's no solution for this. so
This pr changes Coroutine to always run suffixes.

still not tested, but looks good to me.

[Wartori54]

Looks good, I'd like to test it before giving my approval, which I will do at some other time.

[Wartori54]

Self-reminder to update the docs of SwapImmediately at the wiki once this is merged.
LGTM.