Add the option to use markdown on tooltip

[jodinathan]

I would like to add markdown to the tooltip text.
Make some stuff bold etc but not use direct HTML.

I guess you won't add the markdown option, but if you could change some stuff to protected instead of private, then we can extend it and add it ourselves.

[rich-j]

One of the recent additions to Angular Components is the Simple HTML component. I was hoping that the plan is to use <simple-html> in the various components that display text strings (e.g. tooltip, dialog error, etc.).