Tgui say v1.1 (#75431)

## About The Pull Request
"It's better! I promise!"

When I wrote it, I was inexperienced and pretty angry. Not that I'm any
better of a person now, but the code should be. I consolidated instead
of relying on heavy abstractions. I simplified logic and wrote more
tests.

The result should look and feel much more like intended. The bundle size
is reduced by ~43%. Types are much stricter. The logic and css classes
are much more precise.

No major style changes yet
![Screenshot 2023-05-15
003339](https://github.com/tgstation/tgstation/assets/42397676/edeabdcf-5cc6-44ba-9e98-9015bb863547)

## Why It's Good For The Game
Less javascript is better, and being even a few fractions of a second
faster might make better gameplay
## Changelog
🆑
refactor: Tgui Say is rewritten, becoming "much more performant". Hey,
that's what it says on the tin! I'm not from marketing!
fix: Tguisay drag zones are now ever so slightly larger around the
corner of the window
fix: Pressing one of the chat open keys (T/Y/M/O) will no longer change
channels if it's already open
/🆑

code/modules/tgui_input/say_modal/modal.dm

@@ -117,10 +117,10 @@
 		close()
 		return TRUE
 	if (type == "thinking")
-		if(payload["mode"] == TRUE)
+		if(payload["visible"] == TRUE)
 			start_thinking()
 			return TRUE
-		if(payload["mode"] == FALSE)
+		if(payload["visible"] == FALSE)
 			stop_thinking()
 			return TRUE
 		return FALSE