* Splits `renderHtml` into three distict functions to prevent passing in mixed content types
* Moves the `inline` and `className` properties onto the `RenderOptions` structure

- when user opens grunt/gulp/tsconfig file and hasn't run a task, points user to command palette (>tasks)
- add common actions for quickopen

Fixes #29032

* Removes the `child` option for `IHTMLContentElement`. This is only used internally
* Delete some unused functions

fixes #28808