[clang-tools-extra] Add check 'modernize-use-enum-class' (PR #138282)

[Philipp Jung via cfe-commits]

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+.. title:: clang-tidy - modernize-use-enum-class
+
+modernize-use-enum-class
+=============================
+
+Scoped enums (enum class) should be preferred over unscoped enums:
+https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Renum-class
+
+Unscoped enums in classes are not reported since it is a well
+established pattern to limit the scope of plain enums.
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JungPhilipp wrote:

Done

https://github.com/llvm/llvm-project/pull/138282