Add in a settings.experiments module

[sam-phinizy]

This adds in an Experiments model to the Settings class to store all experimental feature settings

Checklist

• This pull request references any related issue by including "closes <link to issue>"
  • If no issue exists and your change is not a small fix, please create an issue first.
• If this pull request adds new functionality, it includes unit tests that cover the changes
• If this pull request removes docs files, it includes redirect settings in mint.json.
• If this pull request adds functions or classes, it includes helpful docstrings.

[codspeed-hq]

CodSpeed Performance Report

Merging #15845 will not alter performance

_{Comparing sam/add-in-experimental-settings (97833c1) with main (8768ffa)}

Summary

✅ 3 untouched benchmarks

[desertaxle]

LGTM!