Simplify HTML for javadoc links

Many methods that create links in javadoc accept a boolean `strong` parameter. Passing `true` for that parameter causes the link label to be wrapped in a `<span>` element with class attribute `type-name-link`. On the other hand, there are many uses of links in javadoc where the link is embedded in a `<span>` element with class attribute `member-name-link`.
Both `type-name-link` and `member-name-link` classes are associated with a single CSS rule to use bold font in `stylesheet.css`.

It seems that the use of separate enclosed or enclosing `<span>` elements is not required since the CSS class could be placed in the link's `<a>` element itself. Furthermore, a boolean `strong` parameter is not a good solution for this purpose. Both issues could be solved by replacing the `strong` parameter with one of type `HtmlStyle`, allowing to directly specify a CSS class for a link.