build(deps): bump highlight.js and typedoc in /tools/doc (#9279)

Removes [highlight.js](https://github.com/highlightjs/highlight.js). It's no longer used after updating ancestor dependency [typedoc](https://github.com/TypeStrong/TypeDoc). These dependencies need to be updated together.


Removes `highlight.js`

Updates `typedoc` from 0.15.8 to 0.25.7
- [Release notes](https://github.com/TypeStrong/TypeDoc/releases)
- [Changelog](https://github.com/TypeStrong/typedoc/blob/master/CHANGELOG.md)
- [Commits](https://github.com/TypeStrong/TypeDoc/compare/v0.15.8...v0.25.7)

---
updated-dependencies:
- dependency-name: highlight.js
  dependency-type: indirect
- dependency-name: typedoc
  dependency-type: direct:production
...

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tools/doc/package.json

@@ -18,7 +18,7 @@
     "remark": "^9.0.0",
     "remark-frontmatter": "^1.2.0",
     "rxjs": "^6.6.6",
-    "typedoc": "^0.15.0",
+    "typedoc": "^0.25.7",
     "typescript": "3.9.8",
     "unist-util-select": "2.0.0"
   },