[clang-tools-extra] [clang-tidy] Adds readability-redundant-const check (PR #189733)

[Baranov Victor via cfe-commits]

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@@ -0,0 +1,23 @@
+// RUN: %check_clang_tidy -std=c23-or-later %s readability-redundant-const %t
+
+const int n1 = 20;
+
+// C23 constexpr
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vbvictor wrote:

```suggestion
```

https://github.com/llvm/llvm-project/pull/189733