Regex should explicitly target IndexOfAnyExcept(char {, char, char}) when handling non-ASCII vectorized sets

[stephentoub]

As of #83992, we're now vectorizing a set like [^Aa], but we're doing so with IndexOfAnyValues when we could instead do so with IndexOfAnyExcept('A', 'a'). IndexOfAnyValues will end up using an implementation that eventually delegates there, but we can skip the intermedaries an additional code gen.

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Issue Details

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As of #83992, we're now vectorizing a set like [^Aa], but we're doing so with IndexOfAnyValues when we could instead do so with IndexOfAnyExcept('A', 'a'). IndexOfAnyValues will end up using an implementation that eventually delegates there, but we can skip the intermedaries an additional code gen.

Author:	stephentoub
Assignees:	-
Labels:	area-System.Text.RegularExpressions
Milestone:	8.0.0