fix(autofmt): remove extra whitespace before commas in for-loop tuple patterns (#5384)

* fix(autofmt): remove extra whitespace before commas in for-loop tuple patterns

`dx fmt` was adding spaces before commas in for-loop destructuring
patterns (e.g. `for (index , name , value)`) because `TokenStream::Display`
inserts spaces between every token. Route the pattern through prettyplease
via a new `unparse_pat` helper, following the existing `unparse_expr` pattern.

Fixes #5348

* style: apply rustfmt to writer.rs

---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

packages/autofmt/tests/samples/forloop_tuple.rsx

@@ -0,0 +1,17 @@
+rsx! {
+    for (index, name, value) in data.iter() {
+        div { "{index}: {name} = {value}" }
+    }
+
+    for item in items {
+        div { "{item}" }
+    }
+
+    for (a, b) in pairs.iter().enumerate() {
+        span { "{a}-{b}" }
+    }
+
+    for (_, value) in pairs {
+        span { "{value}" }
+    }
+}