Changed CachedEntry type from struct to class to avoid unnecessary copies when doing array operations.

Replaced unnecessary array copy in VectorArray class.

Assets/ScriptableRenderPipeline/Core/Shadow/Shadow.cs

 
             public bool IsValid() { return viewport.width > 0 && viewport.height > 0; }
         }
-        protected struct CachedEntry : IComparable<CachedEntry>
+        protected class CachedEntry : IComparable<CachedEntry>
         {
             public Key  key;
             public Data current;

Assets/ScriptableRenderPipeline/Core/Shadow/VectorArray.cs

         {
             for (idx = 0; idx < m_count; ++idx)
             {
-                T obj = this[idx];
-                if (compareDelegate(ref designator, ref obj))
+                if (compareDelegate(ref designator, ref m_array[m_offset + idx]))
                     return true;
             }
             idx = k_InvalidIdx;
         {
             for (idx = 0; idx < m_count; ++idx)
             {
-                if (this[idx].Equals(designator))
+                if (m_array[m_offset + idx].Equals(designator))
                     return true;
             }
             idx = k_InvalidIdx;