[🔥AUDIT🔥] Move Editor component into its own folder (#898)

🖍 _This is an audit!_ 🖍

## Summary:

I noticed that our `Editor` component stories live in the top-level "Editor" folder. This is not even the top-level editor (EditorPage is) so I've moved it into a folder like our other editor stories are. 

<img width="244" alt="image" src="https://github.com/Khan/perseus/assets/77138/ac7b4373-4530-4be8-aea5-d3a68289a6bf">


Issue: --none--

## Test plan:

Author: jeremywiebe

Auditors: #perseus

Required Reviewers:

Approved By:

Checks: ✅ codecov/project, ✅ codecov/patch, ✅ Upload Coverage, ✅ Upload Coverage, ✅ Upload Coverage, ✅ gerald, ⏭  Publish npm snapshot, ✅ Publish Storybook to Chromatic (ubuntu-latest, 20.x), ✅ Check builds for changes in size (ubuntu-latest, 20.x), ✅ Extract i18n strings (ubuntu-latest, 20.x), ✅ Lint, Typecheck, Format, and Test (ubuntu-latest, 20.x), ✅ Cypress (ubuntu-latest, 20.x), ✅ Check for .changeset entries for all changed files (ubuntu-latest, 20.x), ✅ gerald, ✅ Jest Coverage (ubuntu-latest, 20.x), ⏭  Publish npm snapshot, ✅ Check builds for changes in size (ubuntu-latest, 20.x), ✅ Extract i18n strings (ubuntu-latest, 20.x), ✅ Publish Storybook to Chromatic (ubuntu-latest, 20.x), ✅ Lint, Typecheck, Format, and Test (ubuntu-latest, 20.x), ✅ Check for .changeset entries for all changed files (ubuntu-latest, 20.x), ✅ Jest Coverage (ubuntu-latest, 20.x), ✅ gerald, ✅ Cypress (ubuntu-latest, 20.x), ⏭  Publish npm snapshot, ✅ Extract i18n strings (ubuntu-latest, 20.x), ✅ Publish Storybook to Chromatic (ubuntu-latest, 20.x), ✅ Jest Coverage (ubuntu-latest, 20.x), ✅ Check builds for changes in size (ubuntu-latest, 20.x), ✅ Check for .changeset entries for all changed files (ubuntu-latest, 20.x)

Pull Request URL: #898

packages/perseus-editor/src/__stories__/editor.stories.tsx

@@ -14,7 +14,7 @@ import type {PerseusRenderer} from "@khanacademy/perseus";
 registerAllWidgetsAndEditorsForTesting(); // SIDE_EFFECTY!!!! :cry:
 
 export default {
-    title: "Perseus/Editor",
+    title: "Perseus/Editor/Editor",
 };
 
 export const Demo = (): React.ReactElement => {