Completion should offer code style elements in documentation comments

This is a follow-up issue for #35667.

Currently IntelliSense does not offer any of the following elements in completion lists for documentation comments:

* `strong`
* `b`
* `em`
* `i`
* `tt`

All of these elements are currently handled by the presentation style changes in #35667. We should determine which, if any, should be proactively offered to users creating new documentation.