Let Performance/StartWith and Performance/EndWith correct Regexp#match and Regexp#=~

[eugeneius]

Support for String#match? was added in rubocop/rubocop#5744, but not Regexp#match?.

Calling =~ on a regex literal generates a specialised AST node, match-with-lvasgn, to support assigning named captures as local variables. The pattern would previously never match this usage.

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[koic]

Thanks!