Updated control flow type definitions

[sampersand]

Update Kernel "control flow" method definitions:

• catch: (nothing to do)
• throw: make the tag untyped
• at_exit: block return type is void
• exit and exit!: use bool instead of TrueClass | FalseClass; Also, use int instead of Integer for status
• fork: block return type is void, return type in block form is no longer Integer? but just Integer
• loop: block return type is void
• sleep: Add in support for Ruby-3.3.0 preview's sleep(nil)
• raise / fail: Add support for raise has_a_to_str_method, Made the message in the long-form _ToS, and allow for nil and String backtraces.

Technically, the message in the long form can be any type, as long as the first argument's exception function allows for it. So, we could do [T] (_Exception[T], ?T?, ..., but that seems like overkill. (Especially since _Exception is used in Thread and Fiber. Maybe when I get around to I could change the signature?)

[soutaro]

Extra empty line breaks the CI.

[soutaro]

👍