Add Captured Surface Control

[browser-specs-bot]

Close #1568, adding the suggested spec to the list.

Changes to index.json

This update would trigger the following changes in index.json:

Add spec (1)

```json { "url": "https://w3c.github.io/mediacapture-surface-control/", "seriesComposition": "full", "shortname": "mediacapture-surface-control", "series": { "shortname": "mediacapture-surface-control", "currentSpecification": "mediacapture-surface-control", "title": "Captured Surface Control", "shortTitle": "Captured Surface Control", "nightlyUrl": "https://w3c.github.io/mediacapture-surface-control/" }, "organization": "W3C", "groups": [ { "name": "Web Real-Time Communications Working Group", "url": "https://www.w3.org/groups/wg/webrtc/" } ], "nightly": { "url": "https://w3c.github.io/mediacapture-surface-control/", "status": "Editor's Draft", "alternateUrls": [], "repository": "https://github.com/w3c/mediacapture-surface-control", "sourcePath": "index.html", "filename": "index.html" }, "title": "Captured Surface Control", "source": "spec", "shortTitle": "Captured Surface Control", "categories": [ "browser" ], "standing": "good" } ```

Tests

These changes look good! 😎