ruff server now supports source.fixAll source action (#10597)

## Summary

`ruff server` now has source action `source.fixAll` as an available code
action.

This also fixes https://github.com/astral-sh/ruff/issues/10593 in the
process of revising the code for quick fix code actions.

## Test Plan




f4c07425-e68a-445f-a4ed-949c9197a6be

crates/ruff_server/src/fix.rs

@@ -0,0 +1,79 @@
+use ruff_linter::{
+    linter::{FixerResult, LinterResult},
+    settings::{flags, types::UnsafeFixes, LinterSettings},
+    source_kind::SourceKind,
+};
+use ruff_python_ast::PySourceType;
+use ruff_source_file::LineIndex;
+use std::{borrow::Cow, path::Path};
+
+use crate::{
+    edit::{Replacement, ToRangeExt},
+    PositionEncoding,
+};
+
+pub(crate) fn fix_all(
+    document: &crate::edit::Document,
+    linter_settings: &LinterSettings,
+    encoding: PositionEncoding,
+) -> crate::Result<Vec<lsp_types::TextEdit>> {
+    let source = document.contents();
+
+    let source_type = PySourceType::default();
+
+    // TODO(jane): Support Jupyter Notebooks
+    let source_kind = SourceKind::Python(source.to_string());
+
+    // We need to iteratively apply all safe fixes onto a single file and then
+    // create a diff between the modified file and the original source to use as a single workspace
+    // edit.
+    // If we simply generated the diagnostics with `check_path` and then applied fixes individually,
+    // there's a possibility they could overlap or introduce new problems that need to be fixed,
+    // which is inconsistent with how `ruff check --fix` works.
+    let FixerResult {
+        transformed,
+        result: LinterResult { error, .. },
+        ..
+    } = ruff_linter::linter::lint_fix(
+        Path::new("<filename>"),
+        None,
+        flags::Noqa::Enabled,
+        UnsafeFixes::Disabled,
+        linter_settings,
+        &source_kind,
+        source_type,
+    )?;
+
+    if let Some(error) = error {
+        // abort early if a parsing error occurred
+        return Err(anyhow::anyhow!(
+            "A parsing error occurred during `fix_all`: {error}"
+        ));
+    }
+
+    // fast path: if `transformed` is still borrowed, no changes were made and we can return early
+    if let Cow::Borrowed(_) = transformed {
+        return Ok(vec![]);
+    }
+
+    let modified = transformed.source_code();
+
+    let modified_index = LineIndex::from_source_text(modified);
+
+    let source_index = document.index();
+
+    let Replacement {
+        source_range,
+        modified_range,
+    } = Replacement::between(
+        source,
+        source_index.line_starts(),
+        modified,
+        modified_index.line_starts(),
+    );
+
+    Ok(vec![lsp_types::TextEdit {
+        range: source_range.to_range(source, source_index, encoding),
+        new_text: modified[modified_range].to_owned(),
+    }])
+}