Remove benchmark package (#6968)

# Pull Request

## 📖 Description

This change removes `@microsoft/fast-benchmarks` and instead leverages the `@tensile-perf/web-components` package for local perf testing.

### 🎫 Issues

Resolves #6949

## 👩‍💻 Reviewer Notes

This makes a best effort at re-creating benchmarking done between the two methods of benchmarking. All results are still local only and are not published anywhere. That may be a future piece of work so that results may be published and used as part of a build gate workflow.

## ✅ Checklist

### General

<!--- Review the list and put an x in the boxes that apply. -->

- [x] I have included a change request file using `$ yarn change`
- [x] I have added tests for my changes.
- [x] I have tested my changes.
- [ ] I have updated the project documentation to reflect my changes.
- [x] I have read the [CONTRIBUTING](https://github.com/microsoft/fast/blob/master/CONTRIBUTING.md) documentation and followed the [standards](/docs/community/code-of-conduct/#our-standards) for this project.

Author: janechu

.gitignore

@@ -75,3 +75,6 @@ sites/website/i18n/
 # Ignore Build Artefacts
 bin/
 obj/
+
+# Tensile performance test results
+.tensile

change/@microsoft-fast-element-247086ae-c5c2-4272-91e3-508ffa0f54fa.json

@@ -0,0 +1,7 @@
+{
+  "type": "none",
+  "comment": "Update benchmarking to be included in the package instead of being separate",
+  "packageName": "@microsoft/fast-element",
+  "email": "[email protected]",
+  "dependentChangeType": "none"
+}