Formatter: Add SourceType to context to enable special formatting for stub files (#6331)

**Summary** This adds the information whether we're in a .py python
source file or in a .pyi stub file to enable people working on #5822 and
related issues.

I'm not completely happy with `Default` for something that depends on
the input.

**Test Plan** None, this is currently unused, i'm leaving this to first
implementation of stub file specific formatting.

---------

Co-authored-by: Micha Reiser <micha@reiser.io>

crates/ruff_python_formatter/src/cli.rs

@@ -1,14 +1,14 @@
 #![allow(clippy::print_stdout)]
 
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 
 use anyhow::{bail, Context, Result};
 use clap::{command, Parser, ValueEnum};
-use ruff_python_parser::lexer::lex;
-use ruff_python_parser::{parse_tokens, Mode};
 
 use ruff_formatter::SourceCode;
 use ruff_python_index::CommentRangesBuilder;
+use ruff_python_parser::lexer::lex;
+use ruff_python_parser::{parse_tokens, Mode};
 
 use crate::{format_node, PyFormatOptions};
 
@@ -37,7 +37,7 @@ pub struct Cli {
     pub print_comments: bool,
 }
 
-pub fn format_and_debug_print(input: &str, cli: &Cli) -> Result<String> {
+pub fn format_and_debug_print(input: &str, cli: &Cli, source_type: &Path) -> Result<String> {
     let mut tokens = Vec::new();
     let mut comment_ranges = CommentRangesBuilder::default();
 
@@ -57,13 +57,9 @@ pub fn format_and_debug_print(input: &str, cli: &Cli) -> Result<String> {
     let python_ast =
         parse_tokens(tokens, Mode::Module, "<filename>").context("Syntax error in input")?;
 
-    let formatted = format_node(
-        &python_ast,
-        &comment_ranges,
-        input,
-        PyFormatOptions::default(),
-    )
-    .context("Failed to format node")?;
+    let options = PyFormatOptions::from_extension(source_type);
+    let formatted = format_node(&python_ast, &comment_ranges, input, options)
+        .context("Failed to format node")?;
     if cli.print_ir {
         println!("{}", formatted.document().display(SourceCode::new(input)));
     }