Rename ruff_python_whitespace to ruff_python_trivia (#5886)

## Summary

This crate now contains utilities for dealing with trivia more broadly:
whitespace, newlines, "simple" trivia lexing, etc. So renaming it to
reflect its increased responsibilities.

To avoid conflicts, I've also renamed `Token` and `TokenKind` to
`SimpleToken` and `SimpleTokenKind`.

crates/ruff_python_whitespace/src/cursor.rs

@@ -1,103 +0,0 @@
-use std::str::Chars;
-
-use ruff_text_size::{TextLen, TextSize};
-
-pub const EOF_CHAR: char = '\0';
-
-/// A [`Cursor`] over a string.
-#[derive(Debug, Clone)]
-pub struct Cursor<'a> {
-    chars: Chars<'a>,
-    source_length: TextSize,
-}
-
-impl<'a> Cursor<'a> {
-    pub fn new(source: &'a str) -> Self {
-        Self {
-            source_length: source.text_len(),
-            chars: source.chars(),
-        }
-    }
-
-    /// Return the remaining input as a string slice.
-    pub fn chars(&self) -> Chars<'a> {
-        self.chars.clone()
-    }
-
-    /// Peeks the next character from the input stream without consuming it.
-    /// Returns [`EOF_CHAR`] if the file is at the end of the file.
-    pub fn first(&self) -> char {
-        self.chars.clone().next().unwrap_or(EOF_CHAR)
-    }
-
-    /// Peeks the next character from the input stream without consuming it.
-    /// Returns [`EOF_CHAR`] if the file is at the end of the file.
-    pub fn last(&self) -> char {
-        self.chars.clone().next_back().unwrap_or(EOF_CHAR)
-    }
-
-    // SAFETY: THe `source.text_len` call in `new` would panic if the string length is larger than a `u32`.
-    #[allow(clippy::cast_possible_truncation)]
-    pub fn text_len(&self) -> TextSize {
-        TextSize::new(self.chars.as_str().len() as u32)
-    }
-
-    pub fn token_len(&self) -> TextSize {
-        self.source_length - self.text_len()
-    }
-
-    pub fn start_token(&mut self) {
-        self.source_length = self.text_len();
-    }
-
-    /// Returns `true` if the file is at the end of the file.
-    pub fn is_eof(&self) -> bool {
-        self.chars.as_str().is_empty()
-    }
-
-    /// Consumes the next character
-    pub fn bump(&mut self) -> Option<char> {
-        self.chars.next()
-    }
-
-    /// Consumes the next character from the back
-    pub fn bump_back(&mut self) -> Option<char> {
-        self.chars.next_back()
-    }
-
-    pub fn eat_char(&mut self, c: char) -> bool {
-        if self.first() == c {
-            self.bump();
-            true
-        } else {
-            false
-        }
-    }
-
-    pub fn eat_char_back(&mut self, c: char) -> bool {
-        if self.last() == c {
-            self.bump_back();
-            true
-        } else {
-            false
-        }
-    }
-
-    /// Eats symbols while predicate returns true or until the end of file is reached.
-    pub fn eat_while(&mut self, mut predicate: impl FnMut(char) -> bool) {
-        // It was tried making optimized version of this for eg. line comments, but
-        // LLVM can inline all of this and compile it down to fast iteration over bytes.
-        while predicate(self.first()) && !self.is_eof() {
-            self.bump();
-        }
-    }
-
-    /// Eats symbols from the back while predicate returns true or until the beginning of file is reached.
-    pub fn eat_back_while(&mut self, mut predicate: impl FnMut(char) -> bool) {
-        // It was tried making optimized version of this for eg. line comments, but
-        // LLVM can inline all of this and compile it down to fast iteration over bytes.
-        while predicate(self.last()) && !self.is_eof() {
-            self.bump_back();
-        }
-    }
-}