[8pt] Mark all built-in modules with information about yielding

Make fiber stuff well-described again

Product: Tarantool
Since:
Audience/target: Lua devs
Root document: https://www.tarantool.io/en/doc/latest/reference/reference_lua/fiber/
SME: @rosik
Peer reviewer: @ documentarian name

Details

Documentation about implicit cases is very poor. I believe it deserves another chapter in doc.

What information I'd like to see there:

• List ALL functions that yield explicitly. And when do they. For example, channel:get() is tricky and yields only occasionally.
• Mark ALL those functions within their sections - fio, netbox, http, socket, log (!), etc.
• Every implicit yield may raise upon wakeup if the fiber was cancelled.
• fiber.cancel doesn't yield, but still raises "fiber is cancelled" error.
• Please mention requirements for triggers too.

Definition of done

Start with the fiber root document and inventory the explicit and implicit yielding behavior requested there. Review the fio, netbox, http, socket, and log sections, including trigger requirements and cancellation errors. Done means all yielding functions are listed and marked in their sections with their yielding conditions and wakeup behavior.