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>

Content.Client/Decals/UI/PaletteColorPicker.xaml.cs

@@ -0,0 +1,54 @@
+using Content.Shared.Decals;
+using Robust.Client.AutoGenerated;
+using Robust.Client.Graphics;
+using Robust.Client.ResourceManagement;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Client.UserInterface.XAML;
+using Robust.Shared.Prototypes;
+
+namespace Content.Client.Decals.UI;
+
+[GenerateTypedNameReferences]
+public sealed partial class PaletteColorPicker : DefaultWindow
+{
+    [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
+    [Dependency] private readonly IResourceCache _resourceCache = default!;
+
+    private readonly TextureResource _tex;
+
+    public PaletteColorPicker()
+    {
+        RobustXamlLoader.Load(this);
+        IoCManager.InjectDependencies(this);
+
+        _tex = _resourceCache.GetResource<TextureResource>("/Textures/Interface/Nano/button.svg.96dpi.png");
+
+        var i = 0;
+        foreach (var palette in _prototypeManager.EnumeratePrototypes<ColorPalettePrototype>())
+        {
+            Palettes.AddItem(palette.Name);
+            Palettes.SetItemMetadata(i, palette); // ew
+            i += 1;
+        }
+
+        Palettes.OnItemSelected += args =>
+        {
+            Palettes.SelectId(args.Id);
+            SetupList();
+        };
+
+        Palettes.Select(0);
+        SetupList();
+    }
+
+    private void SetupList()
+    {
+        PaletteList.Clear();
+        foreach (var (color, value) in (Palettes.SelectedMetadata as ColorPalettePrototype)!.Colors)
+        {
+            var item = PaletteList.AddItem(color, _tex.Texture);
+            item.Metadata = value;
+            item.IconModulate = value;
+        }
+    }
+}