fix(formatter): treat PrivateFieldExpression as simple call argument

[Dunqing]

Summary

• Treat PrivateFieldExpression (this.#v) as a simple call argument, matching Prettier's behavior where it's a MemberExpression with a PrivateIdentifier
• Without this fix, this.#v as a call argument causes the formatter to break arguments into multiple lines unnecessarily

Before:

this.#t = setInterval(
  () => {
    console.log();
  },
  this.#v,
);

After (matches Prettier):

this.#t = setInterval(() => {
  console.log();
}, this.#v);

Closes #19330

Test plan

• Added test fixture private-field-call-args.ts reproducing the issue
• All 171 formatter tests pass
• Prettier conformance unchanged: JS 746/753 (99.07%), TS 591/601 (98.34%)
• Clippy clean

🤖 Generated with Claude Code

[codspeed-hq]

Merging this PR will not alter performance

✅ 47 untouched benchmarks
⏩ 3 skipped benchmarks¹

---

_{Comparing 02-13-fix_formatter_private_field_simple_argument_19330 (fb4377a) with main (81f0039)}

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[leaysgur]

Merge activity

• Feb 13, 3:02 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Feb 13, 3:09 AM UTC: leaysgur added this pull request to the Graphite merge queue.
• Feb 13, 3:16 AM UTC: Merged by the Graphite merge queue.