Add defineConsts usage to benchmark

[j-malt]

What changed / motivation ?

In #1303 I began adding support for defineConsts to be nested, which requires changing some of the eval code in the Babel plugin. I don't expect that it should harm performance much, but it'd be good to be able to confirm that I'm not introducing a major regression.

This just adds a simple defineConsts usage to the benchmark package in the create-complex file. I'll rebase #1303 on this and add some nested usages.

Additional Context

I'm seeing a pretty significant drop in the "complex create" execs/sec after this change. I suppose that's to be expected.
Main branch

{
  "babel-plugin: stylex.create": {
    "basic create": "1959",
    "complex create": "536"
  },
  "babel-plugin: stylex.createTheme": {
    "basic themes": "1171",
    "complex themes": "100"
  }
}

This branch

{
  "babel-plugin: stylex.create": {
    "basic create": "1927",
    "complex create": "146"
  },
  "babel-plugin: stylex.createTheme": {
    "basic themes": "1200",
    "complex themes": "103"
  }
}

Pre-flight checklist

• I have read the contributing guidelines
  Contribution Guidelines
• Performed a self-review of my code