[llvm] [VPlan] Implement printing VPIRMetadata. (PR #165825)

[via llvm-commits]

ayalz wrote:

> LG, but it seems some recipes were missed, such as the interleave recipe.

Wonder if there's a way to catch/enforce all derived recipes to print their metadata; seems difficult by intercepting `VPValue::printAsOperand()` due to multiple inheritance(?)

https://github.com/llvm/llvm-project/pull/165825