[llvm] VPlan: factor out VPUtils into its own file (NFC) (PR #105857)

[Florian Hahn via llvm-commits]

================
@@ -56,6 +56,7 @@
 #include "llvm/Transforms/Vectorize/LoopVectorize.h"
 #include "LoopVectorizationPlanner.h"
 #include "VPRecipeBuilder.h"
+#include "VPUtils.h"
----------------
fhahn wrote:

```suggestion
#include "VPlanUtils.h"
```

for consistency with other file names in `Vectorize` and avoid confusion with vector predication?

https://github.com/llvm/llvm-project/pull/105857