Pass FormatContext to NeedsParentheses

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## Summary

I started working on this because I assumed that I would need access to options inside of `NeedsParantheses` but it then turned out that I won't. 
Anyway, it kind of felt nice to pass fewer arguments. So I'm gonna put this out here to get your feedback if you prefer this over passing individual fiels. 

Oh, I sneeked in another change. I renamed `context.contents` to `source`. `contents` is too generic and doesn't tell you anything. 

<!-- What's the purpose of the change? What does it do, and why? -->

## Test Plan

It compiles

crates/ruff_python_formatter/src/expression/expr_subscript.rs

@@ -3,8 +3,9 @@ use rustpython_parser::ast::ExprSubscript;
 use ruff_formatter::{format_args, write};
 use ruff_python_ast::node::AstNode;
 
-use crate::comments::{trailing_comments, Comments};
+use crate::comments::trailing_comments;
 use crate::context::NodeLevel;
+use crate::context::PyFormatContext;
 use crate::expression::parentheses::{
     default_expression_needs_parentheses, NeedsParentheses, Parentheses, Parenthesize,
 };
@@ -66,10 +67,9 @@ impl NeedsParentheses for ExprSubscript {
     fn needs_parentheses(
         &self,
         parenthesize: Parenthesize,
-        source: &str,
-        comments: &Comments,
+        context: &PyFormatContext,
     ) -> Parentheses {
-        match default_expression_needs_parentheses(self.into(), parenthesize, source, comments) {
+        match default_expression_needs_parentheses(self.into(), parenthesize, context) {
             Parentheses::Optional => Parentheses::Never,
             parentheses => parentheses,
         }