Account for selector specificity when merging extend_unsafe_fixes and override extend_safe_fixes (#8444)

## Summary

Prior to this change `extend_unsafe_fixes` took precedence over
`extend_safe_fixes` selectors, so any conflicts were resolved in favour
of `extend_unsafe_fixes`. Thanks to that ruff were conservatively
assuming that if configs conlict the fix corresponding to selected rule
will be treated as unsafe.

After this change we take into account Specificity of the selectors. For
conflicts between selectors of the same Specificity we will treat the
corresponding fixes as unsafe. But if the conflicting selectors are of
different specificity the more specific one will win.

## Test Plan

Tests were added for the `FixSafetyTable` struct. The
`check_extend_unsafe_fixes_conflict_with_extend_safe_fixes_by_specificity`
integration test was added to test conflicting rules of different
specificity.

Fixes #8404

---------

Co-authored-by: Zanie <contact@zanie.dev>

crates/ruff_cli/tests/integration_test.rs

@@ -1407,3 +1407,47 @@ extend-safe-fixes = ["UP034"]
 
     Ok(())
 }
+
+#[test]
+fn check_extend_unsafe_fixes_conflict_with_extend_safe_fixes_by_specificity() -> Result<()> {
+    // Adding a rule to one option with a more specific selector should override the other option
+    let tempdir = TempDir::new()?;
+    let ruff_toml = tempdir.path().join("ruff.toml");
+    fs::write(
+        &ruff_toml,
+        r#"
+target-version = "py310"
+[lint]
+extend-unsafe-fixes = ["UP", "UP034"]
+extend-safe-fixes = ["UP03"]
+"#,
+    )?;
+
+    assert_cmd_snapshot!(Command::new(get_cargo_bin(BIN_NAME))
+        .args(["check", "--config"])
+        .arg(&ruff_toml)
+        .arg("-")
+        .args([
+            "--output-format",
+            "text",
+            "--no-cache",
+            "--select",
+            "F601,UP018,UP034,UP038",
+        ])
+        .pass_stdin("x = {'a': 1, 'a': 1}\nprint(('foo'))\nprint(str('foo'))\nisinstance(x, (int, str))\n"),
+            @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    -:1:14: F601 Dictionary key literal `'a'` repeated
+    -:2:7: UP034 Avoid extraneous parentheses
+    -:3:7: UP018 Unnecessary `str` call (rewrite as a literal)
+    -:4:1: UP038 [*] Use `X | Y` in `isinstance` call instead of `(X, Y)`
+    Found 4 errors.
+    [*] 1 fixable with the `--fix` option (3 hidden fixes can be enabled with the `--unsafe-fixes` option).
+
+    ----- stderr -----
+    "###);
+
+    Ok(())
+}