perf(linter/eslint/sort-keys): reserve initial capacity for string (#27624)

We don't allocate any initial capacity for this string, even though the
approximate length of the string can be known ahead of time. This
results in extra reallocations that aren't necessary. By computing the
string capacity, we significantly reduce the number of reallocations.

Not a super significant time or memory win, but this is one of the
highest allocating lint rules.

Running on `vscode`:


Metric | Before | After | Reduction
-- | -- | -- | --
Allocations | 4,071,066 | 4,071,066 | N/A
Reallocations | 2,358,085 | 1,376,677 | 41.6%
Allocated bytes | 882,448,204 | 815,245,566 | 7.6%

crates/oxc_linter/src/rules/eslint/sort_keys.rs

@@ -285,7 +285,20 @@ fn build_object_fix<'a>(
         Cow::Borrowed(" ")
     };
 
-    let mut sorted_text = String::new();
+    let preserve_trailing_comma = matches!(
+        (props.last(), indices.last()),
+        (Some(orig_last), Some(&new_last))
+            if orig_last.consumed_trailing_comma && !props[new_last].consumed_trailing_comma
+    );
+    // Pre-compute the capacity we need for the string so we don't need to re-allocate as we build it.
+    let capacity = props.iter().map(|prop| prop.text.len()).sum::<usize>()
+        + canonical_ws.len() * (indices.len() - 1)
+        + indices[..indices.len() - 1]
+            .iter()
+            .filter(|&&idx| !props[idx].consumed_trailing_comma)
+            .count()
+        + usize::from(preserve_trailing_comma);
+    let mut sorted_text = String::with_capacity(capacity);
     for (slot, &idx) in indices.iter().enumerate() {
         sorted_text.push_str(&props[idx].text);
         if slot + 1 < indices.len() {
@@ -298,10 +311,7 @@ fn build_object_fix<'a>(
 
     // Preserve a trailing comma that was absorbed by the original last prop
     // when the new last prop wouldn't otherwise emit one.
-    if let (Some(orig_last), Some(&new_last)) = (props.last(), indices.last())
-        && orig_last.consumed_trailing_comma
-        && !props[new_last].consumed_trailing_comma
-    {
+    if preserve_trailing_comma {
         sorted_text.push(',');
     }