HtmlDocletWriter contains a non-trivial method, `seeTagToContent`, to handle `@see` and `{@link...}` tags, converting them to `Content`.

This is strange in two ways:

1. The method handles both kinds of tags. While there is a lot of commonality in the handling of `{@link...}` and one of the forms of `@see`, the latter has additional forms that are not related to `{@link...}`. This suggests splitting the method into two "front-end" methods and a shared "back-end" method to handle the case of a `ReferenceTree`, which is the shared common case.

2. The "standard" place for code to translate tags to `Content` is `TagletWriter[Impl]`. This suggests the overall functionality of `seeTagToContent` should be in `TagletWriterImpl`, possibly with appropriate interface methods defined in `TagletWriter`.