[MIRROR] Fix some Section jank disallowing stamps from working properly and messengers from auto-scrolling

[Steals-The-PRs]

Mirrored on Nova: NovaSector/NovaSector#923
Original PR: tgstation/tgstation#81418

About The Pull Request

Alternate title: "A spark of madness drove me to want to fix paperwork tgui"

While doing paperwork I noticed that stamps could not be placed below a certain point on paperwork, just reverting to being higher up. Actually testing this, it seemed the stamps were not accounting for scroll offset in some way.

Images of Stamping Issue

This led me to look into the code, and lo and behold, when PaperSheetStamper in interfaces/PaperSheet.tsx was trying to get the scroll offset from its scrollableRef it was simply returning 0 for scrollTop and 469 for height regardless of what either value should be.
I presumed something was causing the reference to not be properly forwarded from PreviewView's Section to PaperSheetStamper, and continued by testing onScrollHandler.

onScrollHandler seemed to actually have the desired values, and so I made my first naive fix: having PrimaryView instead handle taking the values from onScrollHandler and forwarding them to PaperSheetStamper, and this worked fine!
However, I felt I didn't understand enough about why the reference method didn't work to commit to this approach.

So I went to look deeper, and found that there's actually at least one more thing suffering from this issue.
interfaces/NtosMessenger/ChatScreen.tsx, the PDA messenger.
Specifically, its scrollToBottom method was using a Section reference similarly to our problematic interfaces/PaperSheet.tsx, and wasn't actually working.

Images of PDA Issue

With tens of tabs of React documentation and tg files open went through a crash course in React references, and hey uh- wait, no, hold on. It can't be. Right?

components/Section.tsx was handling two distinct references, forwardedRef and contentRef, in two distinct places. The former, at the highest div, the latter at a lower div... together with onScroll, seemingly confirming my suspicions.
Looking through the file's history, it seems that over the last several prs and reimplementations of parts of this file, the div it was forwarding a reference from was moved from being the same as onScroll to a different div altogether. Then, this became contentRef.

And to confirm this, merging forwardedRef and contentRef seemed to fix the issues with both stamping paperwork and PDA auto-scrolling just fine.

Images of PDA Issues Resolved

Images of Stamping Issues Resolved

Final notes:

• I recognized the issue at play in a moment of madness at 1am, it however still took an extra day for me to feel confident enough in my React to actually fix this without crashing everything else ever.
• Coincidentally "Ace Combat Zero Soundtrack - Zero" was playing in the background while finalizing this.
• For some esoteric reason beyond my current comprehension, as opposed to non-stamped paperwork, stamped paperwork does not auto-focus when scrolled over sometimes. As it already did this before my changes, I am considering it outside of the scope of this pr. It would also most likely deal 3d8 psychic damage, on top of it being 1:53am as of writing this.

Why It's Good For The Game

Reduces paperwork jank, but broadly fixes issues with Section's forwarded reference not actually being a reference to the scrolling part. This includes PDA messengers' scroll to bottom actually working.

Fixes #60508. Given the issue is from 2021 I don't think it's related, but it exists again and hey it works fine now!
Fixes PDA messengers' scroll to bottom actually working.
Fixes, uh, probably other stuff that used to rely on this working.

Changelog

🆑 00-Steven
fix: Fixed stamps not accounting for scroll offset. You can actually stamp paperwork properly without using accursed knowledge again.
fix: Fixed PDA messenger not scrolling to the bottom when a new message gets sent.
/:cl: