Renders the formatted user for a given section on the screen. Please note that the
username may be null (eg for empty fields, anonymous user's, etc) or the user may not exist. Implementations
should handle these cases.
Extra context can be passed to the renderer via the id attribute. Ideally an implementation might include
this id in the rendered output such that it can be used for test assertions.
The result should always be ready to display in an HTML response i.e. it should be HTML encoded if necessary.