[llvm] [VPlan] Add new VPIRPhi overlay for VPIRInsts wrapping phi nodes (NFC). (PR #129387)

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@@ -1033,16 +1033,19 @@ class VPInstruction : public VPRecipeWithIRFlags,
 class VPIRInstruction : public VPRecipeBase {
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ayalz wrote:

The above documentation deserves an update.

https://github.com/llvm/llvm-project/pull/129387