Rename Arguments to Parameters in the AST (#6253)

## Summary

This PR renames a few AST nodes for clarity:

- `Arguments` is now `Parameters`
- `Arg` is now `Parameter`
- `ArgWithDefault` is now `ParameterWithDefault`

For now, the attribute names that reference `Parameters` directly are
changed (e.g., on `StmtFunctionDef`), but the attributes on `Parameters`
itself are not (e.g., `vararg`). We may revisit that decision in the
future.

For context, the AST node formerly known as `Arguments` is used in
function definitions. Formally (outside of the Python context),
"arguments" typically refers to "the values passed to a function", while
"parameters" typically refers to "the variables used in a function
definition". E.g., if you Google "arguments vs parameters", you'll get
some explanation like:

> A parameter is a variable in a function definition. It is a
placeholder and hence does not have a concrete value. An argument is a
value passed during function invocation.

We're thus deviating from Python's nomenclature in favor of a scheme
that we find to be more precise.

crates/ruff_python_formatter/src/other/parameter.rs

@@ -0,0 +1,25 @@
+use crate::prelude::*;
+use crate::FormatNodeRule;
+use ruff_formatter::write;
+use ruff_python_ast::Parameter;
+
+#[derive(Default)]
+pub struct FormatParameter;
+
+impl FormatNodeRule<Parameter> for FormatParameter {
+    fn fmt_fields(&self, item: &Parameter, f: &mut PyFormatter) -> FormatResult<()> {
+        let Parameter {
+            range: _,
+            arg,
+            annotation,
+        } = item;
+
+        arg.format().fmt(f)?;
+
+        if let Some(annotation) = annotation {
+            write!(f, [text(":"), space(), annotation.format()])?;
+        }
+
+        Ok(())
+    }
+}