[clang-tools-extra] [clang-tidy] add new check: modernize-use-scoped-lock (PR #126434)

[Piotr Zegar via cfe-commits]

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+.. title:: clang-tidy - modernize-use-scoped-lock
+
+modernize-use-scoped-lock
+=========================
+
+Finds uses of ``std::lock_guard`` and suggests replacing them with C++17's more
+flexible and safer alternative ``std::scoped_lock``. The check will
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PiotrZSL wrote:

no need for "flexible and safer" here (at least in first sentence).

https://github.com/llvm/llvm-project/pull/126434