Add VRChat and GitHub packages to Unity project

Assets/VRCSDK/Sample Assets/Shaders/Mobile/VRChat-Mobile-Particle-Add.shader

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+// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)
+
+// Simplified Additive Particle shader. Differences from regular Additive Particle one:
+// - no Tint color
+// - no Smooth particle support
+// - no AlphaTest
+// - no ColorMask
+
+Shader "VRChat/Mobile/Particles/Additive"
+{
+    Properties
+    {
+        _MainTex ("Particle Texture", 2D) = "white" {}
+    }
+    
+    Category
+    {
+        Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" "PreviewType"="Plane" }
+        Blend SrcAlpha One
+        Cull Off
+        Lighting Off
+        ZWrite Off
+        Fog { Color (0,0,0,0) }
+    
+        BindChannels
+        {
+            Bind "Color", color
+            Bind "Vertex", vertex
+            Bind "TexCoord", texcoord
+        }
+    
+        SubShader
+        {
+            Pass
+            {
+                SetTexture [_MainTex]
+                {
+                    combine texture * primary
+                }
+            }
+        }
+    }
+}