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_formatter/src/statement/suite.rs

@@ -3,7 +3,7 @@ use rustpython_parser::ast::{Ranged, Stmt, Suite};
 use ruff_formatter::{
     format_args, write, FormatOwnedWithRule, FormatRefWithRule, FormatRuleWithOptions,
 };
-use ruff_python_whitespace::lines_before;
+use ruff_python_trivia::lines_before;
 
 use crate::context::NodeLevel;
 use crate::prelude::*;