feat: CNX-19 adds render material proxy class (#50)

* adds render material proxy class

* Update RenderMaterial.cs

* Update RenderMaterial.cs

* refactors IProxyCollection interface

* Update RenderMaterial.cs

src/Speckle.Core/Models/Instances/GroupProxy.cs

@@ -1,4 +1,4 @@
-namespace Speckle.Core.Models.Instances;
+namespace Speckle.Core.Models.Instances;
 
 /// <summary>
 /// Grouped objects with a meaningful way for host application so use this proxy if you want to group object references for any purpose.
@@ -8,5 +8,8 @@ public class GroupProxy : Base, IProxyCollection
 {
   public List<string> objects { get; set; }
 
+  /// <summary>
+  /// Name of the group proxy collection which is unique for rhino, autocad and sketchup
+  /// </summary>
   public string name { get; set; }
 }

src/Speckle.Core/Models/Instances/IProxyCollection.cs

@@ -1,4 +1,4 @@
-namespace Speckle.Core.Models.Instances;
+namespace Speckle.Core.Models.Instances;
 
 /// <summary>
 /// Collection to proxy objects that lies in definitions, groups or whatever logic in the host app.
@@ -10,9 +10,4 @@ public interface IProxyCollection
   /// On receive, they will be mapped to corresponding newly created definition ids.
   /// </summary>
   public List<string> objects { get; set; }
-
-  /// <summary>
-  /// Name of the proxy collection which is unique for rhino, autocad and sketchup
-  /// </summary>
-  public string name { get; set; }
 }

src/Speckle.Core/Models/Instances/InstanceDefinitionProxy.cs

@@ -12,5 +12,8 @@ public class InstanceDefinitionProxy : Base, IInstanceComponent, IProxyCollectio
 
   public int maxDepth { get; set; }
 
+  /// <summary>
+  /// Name of the instance definition proxy collection which is unique for rhino, autocad and sketchup
+  /// </summary>
   public string name { get; set; }
 }

src/Speckle.Objects/Other/RenderMaterial.cs

@@ -1,6 +1,7 @@
 using System.Drawing;
 using Speckle.Core.Kits;
 using Speckle.Core.Models;
+using Speckle.Core.Models.Instances;
 using Speckle.Newtonsoft.Json;
 
 namespace Objects.Other;
@@ -58,3 +59,27 @@ public class RenderMaterial : Base
     set => diffuse = value.ToArgb();
   }
 }
+
+/// <summary>
+/// Used to store render material to object relationships in root collections
+/// </summary>
+public class RenderMaterialProxy : Base, IProxyCollection
+{
+  public RenderMaterialProxy() { }
+
+  public RenderMaterialProxy(RenderMaterial renderMaterial, List<string> objects)
+  {
+    value = renderMaterial;
+    this.objects = objects;
+  }
+
+  /// <summary>
+  /// The list of application ids of objects that use this render material
+  /// </summary>
+  public List<string> objects { get; set; }
+
+  /// <summary>
+  /// The render material used by <see cref="objects"/>
+  /// </summary>
+  public RenderMaterial value { get; set; }
+}