Integrate SimdUnicode UTF-8 Validation for AdvSimd

[ylpoonlg]

Contributes to #103781, based on #104199.

Includes some changes to reduce code duplication and reuse existing code such as VectorContainsNonAsciiChar to fit in with the library. Most intrinsics are replaced with Vector128 APIs. Otherwise, I tried to encapsulate where platform-specific intrinsics are used so that it will be easier to extend to other Vector128 platforms. That would just require replacing AdvSimd.Arm64.VectorTableLookup with Vector128.Shuffle and some Vector128 replacement for AdvSimd.ExtractVector128, which can be done in a later PR.
The unit tests are also modified to improve the coverage and test cases.

Benchmark results

Neoverse-V2:

Method	Input	Version	Mean	Error	Ratio
GetCharCount	EnglishAllAscii	Before	3.113 us	0.0026 us	1.000
GetCharCount	EnglishAllAscii	After	3.114 us	0.0022 us	1.000
GetCharCount	EnglishMostlyAscii	Before	31.269 us	0.0757 us	1.000
GetCharCount	EnglishMostlyAscii	After	9.970 us	0.0094 us	0.319
GetCharCount	Chinese	Before	34.602 us	0.1955 us	1.000
GetCharCount	Chinese	After	22.637 us	1.1302 us	0.654
GetCharCount	Cyrillic	Before	26.021 us	0.2613 us	1.000
GetCharCount	Cyrillic	After	11.644 us	0.0243 us	0.447
GetCharCount	Greek	Before	66.024 us	0.3077 us	1.000
GetCharCount	Greek	After	15.824 us	0.8816 us	0.240

Neoverse-N2:

Method	Input	Version	Mean	Error	Ratio
GetCharCount	EnglishAllAscii	Before	10.390 us	0.0060 us	1.000
GetCharCount	EnglishAllAscii	After	3.522 us	0.0031 us	0.339
GetCharCount	EnglishMostlyAscii	Before	32.390 us	0.0140 us	1.000
GetCharCount	EnglishMostlyAscii	After	16.587 us	0.0501 us	0.512
GetCharCount	Chinese	Before	46.510 us	0.2420 us	1.000
GetCharCount	Chinese	After	38.449 us	0.0489 us	0.827
GetCharCount	Cyrillic	Before	39.520 us	0.2690 us	1.000
GetCharCount	Cyrillic	After	19.827 us	0.0017 us	0.502
GetCharCount	Greek	Before	85.660 us	0.4650 us	1.000
GetCharCount	Greek	After	26.648 us	0.0026 us	0.311

cc @dotnet/arm64-contrib @lemire @EgorBo @a74nh @SwapnilGaikwad

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-runtime-intrinsics
See info in area-owners.md if you want to be subscribed.