[VPlan] Introduce new VPWidenCallRecipe (NFC).

This patch moves calls to their own recipe, to simplify the transition
to VPUser for operands of VPWidenRecipe, as discussed in D76992.

Subsequently additional information can be added to the recipe rather
than computing it during the execute step.

Reviewers: rengolin, Ayal, gilr, hsaito

Reviewed By: gilr

Differential Revision: https://reviews.llvm.org/D77467