Add Neon implementation of mismatch

[hazzlim]

This PR adds a Neon implementation of mismatch 🚫 🚀

Performance numbers (values are speedup figures relative to existing code; values greater than 1 indicate that the new code is faster):

	MSVC Speedup	Clang Speedup
bm<uint8_t, op::mismatch>/8/3	1.143	0.996
bm<uint8_t, op::mismatch>/24/22	4.083	4.898
bm<uint8_t, op::mismatch>/105/-1	9.333	10.714
bm<uint8_t, op::mismatch>/4021/3056	14.959	15.674
bm<uint16_t, op::mismatch>/8/3	0.918	0.828
bm<uint16_t, op::mismatch>/24/22	3.111	3.683
bm<uint16_t, op::mismatch>/105/-1	5.855	6.6
bm<uint16_t, op::mismatch>/4021/3056	7.438	7.934
bm<uint32_t, op::mismatch>/8/3	0.922	0.715
bm<uint32_t, op::mismatch>/24/22	2.155	2.257
bm<uint32_t, op::mismatch>/105/-1	3.181	3.529
bm<uint32_t, op::mismatch>/4021/3056	3.802	3.967
bm<uint64_t, op::mismatch>/8/3	0.784	0.654
bm<uint64_t, op::mismatch>/24/22	1.434	1.385
bm<uint64_t, op::mismatch>/105/-1	1.789	1.895
bm<uint64_t, op::mismatch>/4021/3056	1.8	1.969
bm<color, op::mismatch, c1, c2>/8/3	0.996	1.071
bm<color, op::mismatch, c1, c2>/24/22	1.021	3.843
bm<color, op::mismatch, c1, c2>/105/-1	1.023	4.906
bm<color, op::mismatch, c1, c2>/4021/3056	1.023	5.06
bm<uint8_t, op::lexi>/8/3	1.128	1.286
bm<uint8_t, op::lexi>/24/22	3.333	4.25
bm<uint8_t, op::lexi>/105/-1	8.609	9.429
bm<uint8_t, op::lexi>/4021/3056	13.659	13.659
bm<int8_t, op::lexi>/8/3	1.08	1.2
bm<int8_t, op::lexi>/24/22	4.838	6.582
bm<int8_t, op::lexi>/105/-1	14.222	17.633
bm<int8_t, op::lexi>/4021/3056	22.36	26.748
bm<uint16_t, op::lexi>/8/3	0.95	1.162
bm<uint16_t, op::lexi>/24/22	4.019	5.378
bm<uint16_t, op::lexi>/105/-1	8.93	11.25
bm<uint16_t, op::lexi>/4021/3056	11.55	13.429
bm<uint32_t, op::lexi>/8/3	0.864	1.056
bm<uint32_t, op::lexi>/24/22	2.689	3.223
bm<uint32_t, op::lexi>/105/-1	5.065	6.098
bm<uint32_t, op::lexi>/4021/3056	5.775	6.508
bm<uint64_t, op::lexi>/8/3	0.736	0.79
bm<uint64_t, op::lexi>/24/22	1.748	2.091
bm<uint64_t, op::lexi>/105/-1	2.784	3.05
bm<uint64_t, op::lexi>/4021/3056	2.795	3.015

[StephanTLavavej]

I'm mirroring this to the MSVC-internal repo. Please notify me if any further changes are pushed, otherwise no action is required.