VecExt added a .map() convenience method on Vec<T> that simply called
.into_iter().map(f).collect(). This thin wrapper provided no
optimisation benefit and obscured a standard iterator pattern behind a
nightly feature gate and an extra dependency.
Replaced the single call site in exo_pyo3_bindings with the equivalent
iterator chain and removed the ext module, the extend dependency, and
the trait_alias feature gate from the util crate.
Test plan:
- CI
The util crate contained several unused items: NonemptyArray,
BoxedSliceExt, a blanket Sealed trait, an empty alias module, six unused
nightly feature gates, and five unused Cargo dependencies (thiserror,
once_cell, internment, derive_more, bon, recursion).
Removed all items that had no references outside their own definitions,
keeping only WakerDeque, VecExt, and the trait_alias feature gate which
are actively used by the networking and exo_pyo3_bindings crates.
Test plan:
- CI
