Cleanup SimdUtils

[JimBobSquarePants]

Prerequisites

• [x] I have written a descriptive pull-request title
• [x] I have verified that there are no overlapping pull-requests open
• [x] I have verified that I am following the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules :cop:.
• [x] I have provided test coverage for my change (where applicable)

Description

The plan here is to be able to remove ExtendedIntrinsics and FallbackIntrinsics128 by normalizing the HwIntrinsics implementation adding Vector512 support and extending Vector128 support to include ARM.

Any and all input is welcome.

CC @tannergooding @saucecontrol @gfoidl @br3aker

[JimBobSquarePants]

Thanks for the review chaps. I've actioned the lot now. Will merge on successful build.

[JimBobSquarePants]

Stating to see some improvement in numbers here.

BenchmarkDotNet v0.13.11, Windows 11 (10.0.22631.3085/23H2/2023Update/SunValley3)
11th Gen Intel Core i7-11370H 3.30GHz, 1 CPU, 8 logical and 4 physical cores
.NET SDK 8.0.101
  [Host]   : .NET 8.0.1 (8.0.123.58001), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  ShortRun : .NET 8.0.1 (8.0.123.58001), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Job=ShortRun  IterationCount=5  LaunchCount=1
WarmupCount=5

Method	Mean	Error	StdDev	Ratio	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
'System.Drawing Load, Resize, Save'	368.56 ms	12.636 ms	1.955 ms	1.00	-	-	-	13.23 KB	1.00
'ImageFlow Load, Resize, Save'	270.28 ms	12.142 ms	3.153 ms	0.74	500.0000	500.0000	500.0000	4642.53 KB	351.00
'ImageSharp Load, Resize, Save'	114.87 ms	2.408 ms	0.625 ms	0.31	-	-	-	1314.02 KB	99.35
'ImageSharp TD Load, Resize, Save'	75.31 ms	1.923 ms	0.499 ms	0.20	166.6667	-	-	1307.22 KB	98.83
'ImageMagick Load, Resize, Save'	393.97 ms	7.115 ms	1.101 ms	1.07	-	-	-	54.48 KB	4.12
'ImageFree Load, Resize, Save'	235.16 ms	2.376 ms	0.617 ms	0.64	6000.0000	6000.0000	6000.0000	95.8 KB	7.24
'MagicScaler Load, Resize, Save'	66.67 ms	0.873 ms	0.135 ms	0.18	-	-	-	45.42 KB	3.43
'SkiaSharp Load, Resize, Save'	136.42 ms	2.833 ms	0.736 ms	0.37	-	-	-	88.15 KB	6.66
'NetVips Load, Resize, Save'	122.52 ms	7.601 ms	1.974 ms	0.33	-	-	-	50.95 KB	3.85