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_parser/src/function.rs

@@ -78,14 +78,18 @@ type FunctionArgument = (
 );
 
 // Parse arguments as supplied during a function/lambda *call*.
-pub(crate) fn parse_args(func_args: Vec<FunctionArgument>) -> Result<ArgumentList, LexicalError> {
+pub(crate) fn parse_arguments(
+    function_arguments: Vec<FunctionArgument>,
+) -> Result<ArgumentList, LexicalError> {
     let mut args = vec![];
     let mut keywords = vec![];
 
-    let mut keyword_names =
-        FxHashSet::with_capacity_and_hasher(func_args.len(), BuildHasherDefault::default());
+    let mut keyword_names = FxHashSet::with_capacity_and_hasher(
+        function_arguments.len(),
+        BuildHasherDefault::default(),
+    );
     let mut double_starred = false;
-    for (name, value) in func_args {
+    for (name, value) in function_arguments {
         if let Some((start, end, name)) = name {
             // Check for duplicate keyword arguments in the call.
             if let Some(keyword_name) = &name {