Introduce an Arguments AST node for function calls and class definitions (#6259)

## Summary

This PR adds a new `Arguments` AST node, which we can use for function
calls and class definitions.

The `Arguments` node spans from the left (open) to right (close)
parentheses inclusive.

In the case of classes, the `Arguments` is an option, to differentiate
between:

```python
# None
class C: ...

# Some, with empty vectors
class C(): ...
```

In this PR, we don't really leverage this change (except that a few
rules get much simpler, since we don't need to lex to find the start and
end ranges of the parentheses, e.g.,
`crates/ruff/src/rules/pyupgrade/rules/lru_cache_without_parameters.rs`,
`crates/ruff/src/rules/pyupgrade/rules/unnecessary_class_parentheses.rs`).

In future PRs, this will be especially helpful for the formatter, since
we can track comments enclosed on the node itself.

## Test Plan

`cargo test`

crates/ruff_python_formatter/src/expression/mod.rs

@@ -356,8 +356,7 @@ impl<'input> CanOmitOptionalParenthesesVisitor<'input> {
             Expr::Call(ast::ExprCall {
                 range: _,
                 func,
-                args: _,
-                keywords: _,
+                arguments: _,
             }) => {
                 self.any_parenthesized_expressions = true;
                 // Only walk the function, the arguments are always parenthesized