Add dimension check when master preview is resized

When themaster review is resized, the new size is checked, and if it has not changed, the rendertexture is not changed.

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Inspector/MasterPreviewView.cs

         {
             RenderTextureDescriptor descriptor = m_PreviewRenderHandle.renderTexture.descriptor;
 
+            var targetWidth = m_PreviewTextureView.contentRect.width;
+            var targetHeight = m_PreviewTextureView.contentRect.height;
+
+            if (Mathf.Approximately(descriptor.width, targetHeight) && Mathf.Approximately(descriptor.height, targetWidth))
+            {
+                return;
+            }
+
+            Object.DestroyImmediate(m_PreviewRenderHandle.renderTexture);
             m_PreviewRenderHandle.renderTexture = new RenderTexture(descriptor);
         }