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

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

* Remove Unused Html Content Renderer Extensibility

Removes a few options from the html content renderer that are currently not used

* Fix messageList

- Refactor configuration services to read settings from multiple folders
- Implement merging strategy for multi root workspace settings
- Implement a configuration model that can be reused across layers
- Implement getRoot API in workspace context service

Fixes Microsoft/vscode-internalbacklog#40

Remove ArraySet and move to native Set