[clang] [analyzer] Add std::variant checker (PR #66481)

[Balazs Benics via cfe-commits]

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@@ -318,6 +318,10 @@ def C11LockChecker : Checker<"C11Lock">,
   Dependencies<[PthreadLockBase]>,
   Documentation<HasDocumentation>;
 
+def StdVariantChecker : Checker<"StdVariant">,
+  HelpText<"Check for bad type access for std::variant.">,
+  Documentation<NotDocumented>;
+
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steakhal wrote:

This needs to be documented.
```suggestion
def StdVariantChecker : Checker<"StdVariant">,
  HelpText<"Check for bad type access for std::variant.">,
  Documentation<Documented>;

```

https://github.com/llvm/llvm-project/pull/66481