[llvm] [LLVM][ADT] Add `consume_front` member to ArrayRef (PR #146741)

[Jakub Kuderski via llvm-commits]

https://github.com/kuhar commented:

Should we also add `consume_back`? I guess this mirrors `consume_front` from `StringRef`, which does support `consume_back`.

https://github.com/llvm/llvm-project/pull/146741