ruff

72257328 - F401 - update documentation and deprecate `ignore_init_module_imports` (#11436)

F401 - update documentation and deprecate `ignore_init_module_imports` (#11436) ## Summary * Update documentation for F401 following recent PRs * #11168 * #11314 * Deprecate `ignore_init_module_imports` * Add a deprecation pragma to the option and a "warn user once" message when the option is used. * Restore the old behavior for stable (non-preview) mode: * When `ignore_init_module_imports` is set to `true` (default) there are no `__init_.py` fixes (but we get nice fix titles!). * When `ignore_init_module_imports` is set to `false` there are unsafe `__init__.py` fixes to remove unused imports. * When preview mode is enabled, it overrides `ignore_init_module_imports`. * Fixed a bug in fix titles where `import foo as bar` would recommend reexporting `bar as bar`. It now says to reexport `foo as foo`. (In this case we don't issue a fix, fwiw; it was just a fix title bug.) ## Test plan Added new fixture tests that reuse the existing fixtures for `__init__.py` files. Each of the three situations listed above has fixture tests. The F401 "stable" tests cover: > * When `ignore_init_module_imports` is set to `true` (default) there are no `__init_.py` fixes (but we get nice fix titles!). The F401 "deprecated option" tests cover: > * When `ignore_init_module_imports` is set to `false` there are unsafe `__init__.py` fixes to remove unused imports. These complement existing "preview" tests that show the new behavior which recommends fixes in `__init__.py` according to whether the import is 1st party and other circumstances (for more on that behavior see: #11314).