Add initial benchmark for parser

[shreyadesai20042009]

📌 Summary

This PR adds an initial benchmark for parser execution using criterion in the benches directory.

🎯 Purpose

The benchmark helps measure the performance of parsing and executing JavaScript code in Boa.
It provides a baseline for future performance improvements and optimizations.

📊 What It Does

Adds a new benchmark file in benches/

Uses criterion for performance measurement

Runs a sample JavaScript workload

Generates performance reports under target/criterion

🚀 How To Run

To run benchmarks:

cargo bench
🔍 Why This Is Useful

Provides a baseline for performance comparison

Helps detect regressions

Supports future optimization work

Improves observability of parser/runtime performance
This benchmark can be extended in future PRs to:

• Compare optimized vs non-optimized mode
• Measure different input sizes
• Benchmark specific parser components

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	49,687	49,666	-21
Ignored	2,262	2,284	+22
Failed	1,014	1,013	-1
Panics	0	0	0
Conformance	93.81%	93.77%	-0.04%

Tested main commit: b3d820369072123ded8defc927405b99b9012648
Tested PR commit: 1251bbd0bc7a64bf78113f9ed616b6f258255a7b
Compare commits: b3d8203...1251bbd