[llvm] Create a CharSetConverter class with both iconv and icu support (PR #74516)

[via llvm-commits]

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@@ -0,0 +1,160 @@
+//===-- CharSet.h - Utility class to convert between char sets ----*- C++ -*-=//
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cor3ntin wrote:

```suggestion
//===-- CharSet.h - Utility class to convert between characters sets ----*- C++ -*-=//
```

https://github.com/llvm/llvm-project/pull/74516