[native_assets_cli] Rename package:hook to package:hooks

[dcharkes]

Bug: #999

A package name is either a verb, a singular noun, or a plural noun. Since this package name is a noun and there is more than one hook (build hook and link hook), rename the package to a plural noun.

[github-actions]

PR Health

Breaking changes ✔️

Package	Change	Current Version	New Version	Needed Version	Looking good?

Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

API leaks ✔️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbols

License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

Files
no missing headers

All source files should start with a license header.

Unrelated files missing license headers

Files
pkgs/jni/lib/src/third_party/generated_bindings.dart
pkgs/objective_c/lib/src/ns_input_stream.dart

[mosuem]

(I assume the name is free or can be freed on pub.dev)

[coveralls]

coverage: 85.954%. remained the same
when pulling 5fe2513 on rename-package-hook
into 540e669 on main.