Move Python whitespace utilities into new ruff_python_whitespace crate (#4993)

## Summary

`ruff_newlines` becomes `ruff_python_whitespace`, and includes the
existing "universal newline" handlers alongside the Python
whitespace-specific utilities.

crates/ruff_python_ast/src/whitespace.rs

@@ -1,6 +1,8 @@
 use ruff_text_size::{TextRange, TextSize};
 use rustpython_parser::ast::Ranged;
 
+use ruff_python_whitespace::is_python_whitespace;
+
 use crate::source_code::Locator;
 
 /// Extract the leading indentation from a line.
@@ -17,41 +19,9 @@ pub fn indentation_at_offset<'a>(locator: &'a Locator, offset: TextSize) -> Opti
     let line_start = locator.line_start(offset);
     let indentation = &locator.contents()[TextRange::new(line_start, offset)];
 
-    if indentation.chars().all(char::is_whitespace) {
+    if indentation.chars().all(is_python_whitespace) {
         Some(indentation)
     } else {
         None
     }
 }
-
-/// Extract the leading words from a line of text.
-pub fn leading_words(line: &str) -> &str {
-    let line = line.trim();
-    line.find(|char: char| !char.is_alphanumeric() && !char.is_whitespace())
-        .map_or(line, |index| &line[..index])
-}
-
-/// Extract the leading whitespace from a line of text.
-pub fn leading_space(line: &str) -> &str {
-    line.find(|char: char| !char.is_whitespace())
-        .map_or(line, |index| &line[..index])
-}
-
-/// Replace any non-whitespace characters from an indentation string.
-pub fn clean(indentation: &str) -> String {
-    indentation
-        .chars()
-        .map(|char| if char.is_whitespace() { char } else { ' ' })
-        .collect()
-}
-
-/// Returns `true` for [whitespace](https://docs.python.org/3/reference/lexical_analysis.html#whitespace-between-tokens)
-/// or new-line characters.
-pub const fn is_python_whitespace(c: char) -> bool {
-    matches!(
-        c,
-        ' ' | '\n' | '\t' | '\r' |
-        // Form-feed
-        '\x0C'
-    )
-}