Extend pragma comment cases (#7687)

## Summary

Extends the pragma comment detection in the formatter to support
case-insensitive `noqa` (as supposed by Ruff), plus a variety of other
pragmas (`isort:`, `nosec`, etc.).

Also extracts the detection out into the trivia crate so that we can
reuse it in the linter (see:
https://github.com/astral-sh/ruff/issues/7471).

## Test Plan

`cargo test`

crates/ruff_python_trivia/src/lib.rs

@@ -1,10 +1,12 @@
 mod comment_ranges;
 mod cursor;
+mod pragmas;
 pub mod textwrap;
 mod tokenizer;
 mod whitespace;
 
 pub use comment_ranges::CommentRanges;
 pub use cursor::*;
+pub use pragmas::*;
 pub use tokenizer::*;
 pub use whitespace::*;

crates/ruff_python_trivia/src/pragmas.rs

@@ -0,0 +1,30 @@
+/// Returns `true` if a comment appears to be a pragma comment.
+///
+/// ```
+/// assert!(ruff_python_trivia::is_pragma_comment("# type: ignore"));
+/// assert!(ruff_python_trivia::is_pragma_comment("# noqa: F401"));
+/// assert!(ruff_python_trivia::is_pragma_comment("# noqa"));
+/// assert!(ruff_python_trivia::is_pragma_comment("# NoQA"));
+/// assert!(ruff_python_trivia::is_pragma_comment("# nosec"));
+/// assert!(ruff_python_trivia::is_pragma_comment("# nosec B602, B607"));
+/// assert!(ruff_python_trivia::is_pragma_comment("# isort: off"));
+/// assert!(ruff_python_trivia::is_pragma_comment("# isort: skip"));
+/// ```
+pub fn is_pragma_comment(comment: &str) -> bool {
+    let Some(content) = comment.strip_prefix('#') else {
+        return false;
+    };
+    let trimmed = content.trim_start();
+
+    // Case-insensitive match against `noqa` (which doesn't require a trailing colon).
+    matches!(
+        trimmed.as_bytes(),
+        [b'n' | b'N', b'o' | b'O', b'q' | b'Q', b'a' | b'A', ..]
+    ) ||
+        // Case-insensitive match against pragmas that don't require a trailing colon.
+        trimmed.starts_with("nosec") ||
+        // Case-sensitive match against a variety of pragmas that _do_ require a trailing colon.
+        trimmed
+        .split_once(':')
+        .is_some_and(|(maybe_pragma, _)| matches!(maybe_pragma, "isort" | "type" | "pyright" | "pylint" | "flake8" | "ruff"))
+}