feat: Central host UI files (#40)

<!--- Provide a general summary of your changes in the Title above -->

## Description

<!--- Describe your changes in detail -->

The **branch** with preview files:

https://github.com/adobe/aem-experimentation/tree/gh-pages


**Todo:**

Configure the adobe.github.io to point to the gh-pages branch.




## Types of changes

<!--- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->

- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)

## Checklist:

<!--- Go over all the following points, and put an `x` in all the boxes
that apply. -->
<!--- If you're unsure about any of these, don't hesitate to ask. We're
here to help! -->

- [x] I have signed the [Adobe Open Source
CLA](https://opensource.adobe.com/cla.html).
- [x] My code follows the code style of this project.
- [ ] My change requires a change to the documentation.
- [ ] I have updated the documentation accordingly.
- [x] I have read the **CONTRIBUTING** document.
- [ ] I have added tests to cover my changes.
- [ ] All new and existing tests passed.

---------

Co-authored-by: Julien Ramboz <[email protected]>

package.json

@@ -4,7 +4,7 @@
   "main": "src/index.js",
   "scripts": {
     "lint:js": "eslint src",
-    "lint:css": "stylelint src/**/*.css",
+    "lint:css": "stylelint src/**/*.css --allow-empty-input",
     "lint": "npm run lint:js && npm run lint:css",
     "start": "http-server . -p 3000",
     "test": "playwright test"

src/index.js

@@ -917,7 +917,12 @@ export async function loadLazy(document, options = {}) {
   if (!isDebugEnabled) {
     return;
   }
-  // eslint-disable-next-line import/no-cycle
-  const preview = await import('./preview.js');
-  preview.default(document, pluginOptions);
+  // eslint-disable-next-line import/no-unresolved
+  const preview = await import('https://opensource.adobe.com/aem-experimentation/preview.js');
+  const context = {
+    getMetadata,
+    toClassName,
+    debug,
+  };
+  preview.default.call(context, document, pluginOptions);
 }