[LV] Add VPBuilder::insert, use to insert created vector pointer (NFC).

Split off from #124432 as
suggested. Adds VPBuilder::insert, inspired by IRBuilderBase.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h

@@ -141,6 +141,9 @@ class VPBuilder {
     InsertPt = IP->getIterator();
   }
 
+  /// Insert \p R at the current insertion point.
+  void insert(VPRecipeBase *R) { BB->insert(R, InsertPt); }
+
   /// Create an N-ary operation with \p Opcode, \p Operands and set \p Inst as
   /// its underlying Instruction.
   VPInstruction *createNaryOp(unsigned Opcode, ArrayRef<VPValue *> Operands,

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -8323,7 +8323,7 @@ VPRecipeBuilder::tryToWidenMemory(Instruction *I, ArrayRef<VPValue *> Operands,
                                                 : GEPNoWrapFlags::none(),
                                             I->getDebugLoc());
     }
-    Builder.getInsertBlock()->appendRecipe(VectorPtr);
+    Builder.insert(VectorPtr);
     Ptr = VectorPtr;
   }
   if (LoadInst *Load = dyn_cast<LoadInst>(I))