Add Arm benchmark

tests/ImageSharp.Benchmarks/Codecs/Jpeg/ColorConversion/RgbColorConversion.cs

@@ -37,4 +37,12 @@ public class RgbColorConversion : ColorConversionBenchmark
 
         new JpegColorConverterBase.RgbAvx(8).ConvertToRgbInplace(values);
     }
+
+    [Benchmark]
+    public void SimdVectorArm()
+    {
+        var values = new JpegColorConverterBase.ComponentValues(this.Input, 0);
+
+        new JpegColorConverterBase.RgbArm(8).ConvertToRgbInplace(values);
+    }
 }