[isort] Add support for length-sort settings (#8841)

## Summary

Closes #1567.

Add both `length-sort` and `length-sort-straight` settings for isort.

Here are a few notable points:
- The length is determined using the
[`unicode_width`](https://crates.io/crates/unicode-width) crate, i.e. we
are talking about displayed length (this is explicitly mentioned in the
description of the setting)
- The dots are taken into account in the length to be compatible with
the original isort
- I had to reorder a few fields of the module key struct for it all to
make sense (notably the `force_to_top` field is now the first one)

## Test Plan

I added tests for the following cases:
- Basic tests for length-sort with ASCII characters only
- Tests with non-ASCII characters
- Tests with relative imports
- Tests for length-sort-straight

crates/ruff_workspace/src/options.rs

@@ -2047,6 +2047,40 @@ pub struct IsortOptions {
     )]
     pub from_first: Option<bool>,
 
+    /// Sort imports by their string length, such that shorter imports appear
+    /// before longer imports. For example, by default, imports will be sorted
+    /// alphabetically, as in:
+    /// ```python
+    /// import collections
+    /// import os
+    /// ```
+    ///
+    /// Setting `length-sort = true` will instead sort such that shorter imports
+    /// appear before longer imports, as in:
+    /// ```python
+    /// import os
+    /// import collections
+    /// ```
+    #[option(
+        default = r#"false"#,
+        value_type = "bool",
+        example = r#"
+            length-sort = true
+        "#
+    )]
+    pub length_sort: Option<bool>,
+
+    /// Sort straight imports by their string length. Similar to `length-sort`,
+    /// but applies only to straight imports and doesn't affect `from` imports.
+    #[option(
+        default = r#"false"#,
+        value_type = "bool",
+        example = r#"
+            length-sort-straight = true
+        "#
+    )]
+    pub length_sort_straight: Option<bool>,
+
     // Tables are required to go last.
     /// A list of mappings from section names to modules.
     /// By default custom sections are output last, but this can be overridden with `section-order`.
@@ -2234,6 +2268,8 @@ impl IsortOptions {
             section_order,
             no_sections,
             from_first,
+            length_sort: self.length_sort.unwrap_or(false),
+            length_sort_straight: self.length_sort_straight.unwrap_or(false),
         })
     }
 }