Expands the SS13.lua module by adding loop helpers and functions to get the script runner. (#79081)

## About The Pull Request
`SS13.get_runner_client()` and `SS13.get_runner_ckey` will return the
client and the ckey respectively of the user who ran the lua script. Can
be unreliable after the first sleep or yield.
The SS13 module can now be made local as the tables that need to be
accessed globally have been moved to their own global variables.
Added `SS13.start_loop(time, amount, func)`, `SS13.end_loop(id)`,
`SS13.stop_all_loops()` that allow lua scripts to more easily make
loops. Removed the `timer` parameter from these functions, which
specified the timer subsystem to use.
Documentation on all new added functions have been added in the
lua/README.md

## Why It's Good For The Game
Getting the client who ran the script and the ckey that ran the script
is useful for self contained scripts that are looking for an entrypoint
(e.g. location to spawn some item/mob/structure). `dm.usr` is a special
variable used for other purposes and can be unreliable when used this
way even if there haven't been any sleeps or yields yet, so having a
dedicated variable and function to handle it makes things easier.

Being able to make the SS13 module local allows for more self-contained
scripts. Although this isn't super helpful because `require` will still
load the same object for all lua scripts loaded on the same state.

Basic looping helpers allow for lua scripts to more easily create loops
without needing to recursively do a `set_timeout` or to do a
`while(true) do SS13.wait(1) end` loop.

## Changelog
🆑
admin: Added SS13.get_runner_ckey() and SS13.get_runner_client() which
stores the ckey and returns the client of the user who ran the lua
script. Can be unreliable if accessed after sleeping.
admin: Added timer loop helpers to the SS13.lua module, check the docs
admin: The SS13.lua module can now be made local without causing any
errors.
/🆑

---------

Co-authored-by: Watermelon914 <3052169-Watermelon914@users.noreply.gitlab.com>

code/modules/admin/verbs/lua/lua_editor.dm

@@ -126,6 +126,7 @@
 			return TRUE
 		if("runCode")
 			var/code = params["code"]
+			current_state.ckey_last_runner = usr.ckey
 			var/result = current_state.load_script(code)
 			var/index_with_result = current_state.log_result(result)
 			message_admins("[key_name(usr)] executed [length(code)] bytes of lua code. [ADMIN_LUAVIEW_CHUNK(current_state, index_with_result)]")