…y to

…ability; remove unnecessary pattern match

…urn a fix if imports were actually given

… either moves to __all__ or makes imports explicit

… two groups of import statement bindings; then iterate over those bindings and the fix which applies to them

…ework after discussion w/zanie

… api

…test

… fixtures

… api

…test

… fixtures

…sable F401 based on deprecated flag, but use the preview flag; move the testcases down to the preview testcase section; move the insta-snapshots to the preview paths

… test and add a test-case for the preview linter rules that references that fixture; move its insta-snapshot to the location used by the new test-case

…pdate generation of help messages

…when deciding how to fix them

…of slices

…h to make explicit-exports (#11168)

Resolves #10390 and starts to address #10391

# Changes to behavior

* In `__init__.py` we now offer some fixes for unused imports.
* If the import binding is first-party this PR suggests a fix to turn it
into a redundant alias.
* If the import binding is not first-party, this PR suggests a fix to
remove it from the `__init__.py`.
* The fix-titles are specific to these new suggested fixes.
* `checker.settings.ignore_init_module_imports` setting is
deprecated/ignored. There is probably a documentation change to make
that complete which I haven't done.

---

<details><summary>Old description of implementation changes</summary>

# Changes to the implementation

* In the body of the loop over import statements that contain unused
bindings, the bindings are partitioned into `to_reexport` and
`to_remove` (according to how we want to resolve the fact they're
unused) with the following predicate:
  ```rust
in_init && is_first_party(checker, &import.qualified_name().to_string())
// true means make it a reexport
  ```
* Instead of generating a single fix per import statement, we now
generate up to two fixes per import statement:
  ```rust
  (fix_by_removing_imports(checker, node_id, &to_remove, in_init).ok(),
   fix_by_reexporting(checker, node_id, &to_reexport, dunder_all).ok())
  ```
* The `to_remove` fixes are unsafe when `in_init`.
* The `to_explicit` fixes are safe. Currently, until a future PR, we
make them redundant aliases (e.g. `import a` would become `import a as
a`).

## Other changes

* `checker.settings.ignore_init_module_imports` is deprecated/ignored.
Instead, all fixes are gated on `checker.settings.preview.is_enabled()`.
* Got rid of the pattern match on the import-binding bound by the inner
loop because it seemed less readable than referencing fields on the
binding.
* [x] `// FIXME: rename "imports" to "bindings"` if reviewer agrees (see
code)
* [x] `// FIXME: rename "node_id" to "import_statement"` if reviewer
agrees (see code)

<details>
<summary><h2>Scope cut until a future PR</h2></summary>

* (Not implemented) The `to_explicit` fixes will be added to `__all__`
unless it doesn't exist. When `__all__` doesn't exist they're resolved
by converting to redundant aliases (e.g. `import a` would become `import
a as a`).
 
---

</details>

# Test plan

* [x] `crates/ruff_linter/resources/test/fixtures/pyflakes/F401_24`
contains an `__init__.py` with*out* `__all__` that exercises the
features in this PR, but it doesn't pass.
* [x]
`crates/ruff_linter/resources/test/fixtures/pyflakes/F401_25_dunder_all`
contains an `__init__.py` *with* `__all__` that exercises the features
in this PR, but it doesn't pass.
* [x] Write unit tests for the new edit functions in
`fix::edits::make_redundant_alias`.

</details>

---------

Co-authored-by: Micha Reiser <micha@reiser.io>