Holographic hoverbeds & Rollerbed/Bodybag tweaks

[Dragometh]

About the PR

This PR is a series of PRs cherry picked.
It consists of:

• Cherry-pick of Delta-V's ERT overhaul
  • More specifically, the holographic hoverbed; Sprites and related prototype.
• Cherry-pick of #40550: Fix Rollerbed sprites
• Cherry-pick of #40880: Rollerbed & Bodybag tweaks
• Cherry-pick of Delta-V's Remake Holographic Rollerbed

In a nutshell:

• Adds holographic rollerbeds, with a density of 5 - These also have a very weak point light to them, fit in a 1x2 when folded, and look really cool! They are researchable alongside moon boots.
• Fixes roller beds having double sprite when having someone buckled to (check #40550)
• Adjusts rollerbeds and body bag densities: Body bags now have a density of 80, whereas roller beds have 20

Why / Balance

Holographic rollerbeds look really cool and might be an motivator for players to actually start using roller beds and not dragging their patients off the floor (we should really add blood smears...)
Rollerbeds and body bag density changes: Because something with wheels should be easier to drag than something that's literally being frictionned throughout all floors you bring it through.

Technical details

Mostly YML changes, except for the holo rollerbed's point light addition on the FoldableSystem.

How to test

1. Be in reach of a sci setup (server, console, blueprint litho)
2. Add points to server; Research moon boots tech.
3. Make a medical blueprint from blueprint litho
4. Add it to a medfab. You might need to source one.
5. Look for "holographic hoverbed". You can now make one!
6. Make one. Unfold it. Strap yourself or a Urist in it. Be amazed.

Media

Requirements

• I have read CONTRIBUTING.md and and am following the Pull Request and Changelog Guidelines.
• I have added media to this PR or it does not require an ingame showcase.
• I have reviewed the Ship Submission Guidelines if relevant.
• I confirm that AI tools were not used in generating the material in this PR.

Breaking changes

So apparently, due to the density changes, this makes regular rollerbeds die to armed mouse traps; they deal 187 damage to it. See #43330 for more info.
This shouldn't be that big of an issue considering this is a Frontier fork and the chances of someone rolling a rollerbed over a mousetrap are slim to none, but not null, so it should be kept in mind as a known bug.

Changelog

🆑

• add: Holographic Hoverbeds! They can be researched and built from a medfab. (by SirWarock on github!)
• tweak: Changes to rollerbeds and body bag densities. The one with wheels should be easier to drag than the one without, now. (also by SirWarock!)

[github-actions]

RSI Diff Bot; head commit 5c09dc1 merging into 6dba21e
This PR makes changes to 1 or more RSIs. Here is a summary of all changes:

Resources/Textures/_DV/Structures/Furniture/rollerbeds.rsi

State	Old	New	Status
holographic_hoverbed_buckled_shaded			Added
holographic_hoverbed_buckled_unshaded			Added
holographic_hoverbed_folded_shaded			Added
holographic_hoverbed_folded_unshaded			Added
holographic_hoverbed_shaded			Added
holographic_hoverbed_unshaded			Added

Edit: diff updated after 5c09dc1