Rename OOM to allocation error

Rename OOM to allocation error

The acronym is not descriptive unless one has seen it before.

* Rename the `oom` function to `handle_alloc_error`. It was **stabilized in 1.28**, so if we do this at all we need to land it this cycle.
* Rename `set_oom_hook` to `set_alloc_error_hook`
* Rename `take_oom_hook` to `take_alloc_error_hook`

Bikeshed: `alloc` v.s. `allocator`, `error` v.s. `failure`