[llvm] [NFC] Replace `GetPatFromTreePatternNode` with `llvm::to_string` (PR #123754)

[Tomas Matheson via llvm-commits]

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@@ -22,6 +22,7 @@
 #include "llvm/ADT/TinyPtrVector.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/ScopedPrinter.h" // for llvm::to_string
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tmatheson-arm wrote:

Any suggestions for a better place for `llvm::to_string()` to live?

https://github.com/llvm/llvm-project/pull/123754