Decal Placer + add new decals for mapping (#6548)

* abomination

* okay its less unabashedly garbage now

* other UI changes

* its britney bitch

* proper greyscale full/half/quarter tiles

* misc cleanup

* rsi

* Add a palette system. It's Kara's problem now.

* oops

* a

* Departmental palette alpha tweaks

* oopy

* so true

* Update Content.Shared/Decals/ColorPalettePrototype.cs

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

* fixes for that

* neutral light color and new warning lines

* dirt

* checkerboards

* oop

Co-authored-by: moonheart08 <moonheart08@users.noreply.github.com>
Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Resources/Locale/en-US/sandbox/sandbox-manager.ftl

@@ -2,6 +2,7 @@ sandbox-window-title = Sandbox Panel
 sandbox-window-respawn-button = Respawn
 sandbox-window-spawn-entities-button = Spawn Entities
 sandbox-window-spawn-tiles-button = Spawn Tiles
+sandbox-window-spawn-decals-button = Spawn Decals
 sandbox-window-grant-full-access-button = Grant Full Access
 sandbox-window-ghost-button = Ghost
 sandbox-window-toggle-lights-button = Toggle Lights
@@ -11,4 +12,4 @@ sandbox-window-toggle-subfloor-button = Toggle Subfloor
 sandbox-window-toggle-suicide-button = Suicide
 sandbox-window-show-spawns-button = Shows Spawns
 sandbox-window-show-bb-button = Show BB
-sandbox-window-link-machines-button = Link machines
+sandbox-window-link-machines-button = Link machines