Adding embroider tests to testing metrics

[kiwiupover]

ember-cli-addon-docs need to be deployed
ember-learn/ember-cli-addon-docs#474

After ember-cli-addon-docs are updated the next errors.

@ef4 when testing with embroider it looks like a few addons are including @babel/plugin-proposal-optional-chaining
Resolving to a single version in the package.json does not fix the issue.

ERROR Summary:
  - broccoliBuilderErrorStack: ModuleBuildError: Module build failed (from /Users/kiwi/projects/ember-app-scheduler/node_modules/thread-loader/dist/cjs.js):
Thread Loader (Worker 0)
Duplicate plugin/preset detected.
If you'd like to use two separate instances of a plugin,
they need separate names, e.g.

  plugins: [
    ['some-plugin', {}],
    ['some-plugin', {}, 'some unique name'],
  ]

Duplicates detected are:
[
  {
    "alias": "/Users/kiwi/projects/ember-app-scheduler/node_modules/@babel/plugin-proposal-optional-chaining/lib/index.js",
    "dirname": "/Users/kiwi/projects/ember-app-scheduler",
    "ownPass": false,
    "file": {
      "request": "/Users/kiwi/projects/ember-app-scheduler/node_modules/@babel/plugin-proposal-optional-chaining/lib/index.js",
      "resolved": "/Users/kiwi/projects/ember-app-scheduler/node_modules/@babel/plugin-proposal-optional-chaining/lib/index.js"
    }
  },
  {
    "alias": "/Users/kiwi/projects/ember-app-scheduler/node_modules/@babel/plugin-proposal-optional-chaining/lib/index.js",
    "dirname": "/Users/kiwi/projects/ember-app-scheduler",
    "ownPass": false,
    "file": {
      "request": "/Users/kiwi/projects/ember-app-scheduler/node_modules/@babel/plugin-proposal-optional-chaining/lib/index.js",
      "resolved": "/Users/kiwi/projects/ember-app-scheduler/node_modules/@babel/plugin-proposal-optional-chaining/lib/index.js"
    }
  }
]

[ef4]

I think this is the same issue as embroider-build/embroider#453