Enable support for highlighting TypeScript code

[mgrebenets]

Bug/issue #, if applicable: N/A

Summary

JavaScript is already supported.
TypeScript is very popular language as well.
Supporting highlight requires minimal changes since highlight.js library already supports the language.

Dependencies

No new dependencies added.

Testing

Steps:

1. Add block of TypeScript code to SwiftDocCRender.docc/contributing/Internals.md, e.g.

## Syntax Highlighting

```typescript
import example from "example";

const value = 100;
```

2. Build doccarchive: xcrun docc convert SwiftDocCRender.docc -o out.doccarchive
3. Point dev server proxy to built docarchive: VUE_APP_DEV_SERVER_PROXY=/path/to/swift-docc-render/out.doccarchive
4. npm run serve
5. Browse http://localhost:8080/documentation/internals
6. Check TypeScript highlight

Checklist

Make sure you check off the following items. If they cannot be completed, provide a reason.

• Added tests (Not applicable)
• Ran npm test, and it succeeded
• Updated documentation if necessary

[mportiz08]

@swift-ci test