Fix DPI scaling with TGUI, TGUI Say, and Tooltips (#20734)

Got tired of the issues here when working on something else.

Ported several PRs from /tg/station to fix DPI scaling issues. This was
not a problem before 516, however 516 now respects Window's DPI setting,
causing misalignment in several of our UI elements.

This PR implements these ~~four~~ ~~five~~ six PRs:
https://github.com/tgstation/tgstation/pull/65686
https://github.com/tgstation/tgstation/pull/89994
https://github.com/tgstation/tgstation/pull/90416
https://github.com/tgstation/tgstation/pull/90418
https://github.com/tgstation/tgstation/pull/90796
https://github.com/cmss13-devs/cmss13/pull/8734

~~Does not include fixes with TGUI-Say. /tg/station refactored TGUI-Say
after their port to React before they fixed DPI scaling, and this would
be pain to deconstruct to port over to Inferno. Since porting to React
is "inevitable", I considered it not worth my time to fix this.~~

Thanks to the assistance of harry, TGUI-Say fixes now included.

code/modules/error_handler/error_viewer.dm

@@ -27,7 +27,7 @@ GLOBAL_DATUM(error_cache, /datum/error_viewer/error_cache)
 /datum/error_viewer/proc/browse_to(client/user, html)
 	var/datum/browser/browser = new(user.mob, "error_viewer", null, 600, 400)
 	browser.set_content(html)
-	browser.add_head_content({"
+	browser.set_head_content({"
 	<style>
 	.runtime
 	{