[Analyzer]: Regex.Match(...).Success to Regex.IsMatch

[stephentoub]

I see a non-trivial amount of code that does Regex.Match(...).Success rather than Regex.IsMatch(...). The latter is functionally equivalent but more efficient, as it doesn't need to compute full match boundaries, doesn't need to compute capture groups, and doesn't need to allocate a Match object and supporting data structures. We should have an analyzer that looks for the former and a fixer that translates it into the latter. It should apply to both instance and static methods, everywhere there's a Match overload with arguments that have an exactly corresponding IsMatch overload.

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