Update identifier Unicode character validation to match Python spec

[zanieb]

Python supports some, but not all Unicode characters in identifiers. See https://docs.python.org/3/reference/lexical_analysis.html#identifiers and https://peps.python.org/pep-3131/

However, Ruff is not correctly enforcing the subset of valid unicode characters e.g. in is_identifier

ruff/crates/ruff_python_stdlib/src/identifiers.rs

Lines 3 to 23 in 1df7e98

	/// Returns `true` if a string is a valid Python identifier (e.g., variable
	/// name).
	pub fn is_identifier(name: &str) -> bool {
	// Is the first character a letter or underscore?
	let mut chars = name.chars();
	if !chars.next().is_some_and(|c| c.is_alphabetic() || c == '_') {
	return false;
	}
	// Are the rest of the characters letters, digits, or underscores?
	if !chars.all(|c| c.is_alphanumeric() || c == '_') {
	return false;
	}
	// Is the identifier a keyword?
	if is_keyword(name) {
	return false;
	}
	true
	}

This causes bugs such as:

• Rule B009 cause autofix error #7156
• Rule B010 cause autofix error #7157

We need to add validation of the specific supported subset of characters.

[MichaReiser]

The relevant function in our lexer

ruff/crates/ruff_python_parser/src/lexer.rs

Lines 1182 to 1187 in 4d49d5e

	fn is_identifier_continuation(c: char) -> bool {
	match c {
	'a'..='z' | 'A'..='Z' | '_' | '0'..='9' => true,
	c => is_xid_continue(c),
	}
	}

[LaBatata101]

I can work on this one