[isort] Insert imports in alphabetical order (I002) (#22493)

<!--
Thank you for contributing to Ruff/ty! To help us out with reviewing,
please consider the following:

- Does this pull request include a summary of the change? (See below.)
- Does this pull request include a descriptive title? (Please prefix
with `[ty]` for ty pull
  requests.)
- Does this pull request include references to any relevant issues?
-->

## Summary

<!-- What's the purpose of the change? What does it do, and why? -->
This PR fixes #20811 , current approach reverses the order in `BtreeSet`
however as pointed in
https://github.com/astral-sh/ruff/issues/20811#issuecomment-3398958832
here we cannot use I`IndexSet` to preserve config order since Settings
derives `CacheKey` which isn't implemented for `IndexSet`, another
approach to preserve the original order might be to use `Vec` however
lookup time complexity might get affected as a result.

<!-- How was it tested? -->
I have tested it locally its working as expected ,
<img width="2200" height="1071" alt="image"
src="https://github.com/user-attachments/assets/7d97b488-1552-4a42-9d90-92acf55ec493"
/>

---------

Signed-off-by: Bhuminjay <bhuminjaysoni@gmail.com>

crates/ruff_linter/src/rules/isort/rules/add_required_imports.rs

@@ -140,7 +140,7 @@ pub(crate) fn add_required_imports(
     source_type: PySourceType,
     context: &LintContext,
 ) {
-    for required_import in &settings.isort.required_imports {
+    for required_import in settings.isort.required_imports.iter().rev() {
         add_required_import(
             required_import,
             parsed,

crates/ruff_linter/src/rules/isort/snapshots/ruff_linter__rules__isort__tests__required_imports_docstring.py.snap

@@ -1,14 +1,6 @@
 ---
 source: crates/ruff_linter/src/rules/isort/mod.rs
 ---
-I002 [*] Missing required import: `from __future__ import annotations`
---> docstring.py:1:1
-help: Insert required import: `from __future__ import annotations`
-1 | """Hello, world!"""
-2 + from __future__ import annotations
-3 | 
-4 | x = 1
-
 I002 [*] Missing required import: `from __future__ import generator_stop`
 --> docstring.py:1:1
 help: Insert required import: `from __future__ import generator_stop`
@@ -16,3 +8,11 @@ help: Insert required import: `from __future__ import generator_stop`
 2 + from __future__ import generator_stop
 3 | 
 4 | x = 1
+
+I002 [*] Missing required import: `from __future__ import annotations`
+--> docstring.py:1:1
+help: Insert required import: `from __future__ import annotations`
+1 | """Hello, world!"""
+2 + from __future__ import annotations
+3 | 
+4 | x = 1

crates/ruff_linter/src/rules/isort/snapshots/ruff_linter__rules__isort__tests__required_imports_multiple_strings.py.snap

@@ -1,15 +1,6 @@
 ---
 source: crates/ruff_linter/src/rules/isort/mod.rs
 ---
-I002 [*] Missing required import: `from __future__ import annotations`
---> multiple_strings.py:1:1
-help: Insert required import: `from __future__ import annotations`
-1 | """This is a docstring."""
-2 + from __future__ import annotations
-3 | "This is not a docstring."
-4 | "This is also not a docstring."
-5 | 
-
 I002 [*] Missing required import: `from __future__ import generator_stop`
 --> multiple_strings.py:1:1
 help: Insert required import: `from __future__ import generator_stop`
@@ -17,4 +8,13 @@ help: Insert required import: `from __future__ import generator_stop`
 2 + from __future__ import generator_stop
 3 | "This is not a docstring."
 4 | "This is also not a docstring."
+5 | 
+
+I002 [*] Missing required import: `from __future__ import annotations`
+--> multiple_strings.py:1:1
+help: Insert required import: `from __future__ import annotations`
+1 | """This is a docstring."""
+2 + from __future__ import annotations
+3 | "This is not a docstring."
+4 | "This is also not a docstring."
 5 |

crates/ruff_linter/src/rules/pyupgrade/mod.rs

@@ -398,17 +398,17 @@ mod tests {
         1 + from pipes import Template
         2 + from shlex import quote
 
-        I002 [*] Missing required import: `from __future__ import generator_stop`
-        --> <filename>:1:1
-        help: Insert required import: `from __future__ import generator_stop`
-        1 + from __future__ import generator_stop
-        2 | from pipes import quote, Template
-
         I002 [*] Missing required import: `from collections import Sequence`
         --> <filename>:1:1
         help: Insert required import: `from collections import Sequence`
         1 + from collections import Sequence
         2 | from pipes import quote, Template
+
+        I002 [*] Missing required import: `from __future__ import generator_stop`
+        --> <filename>:1:1
+        help: Insert required import: `from __future__ import generator_stop`
+        1 + from __future__ import generator_stop
+        2 | from pipes import quote, Template
         ");
     }