Use <wbr> instead of ZERO_WIDTH_SPACE

javadoc currently uses an entity ( `&#8203;`) for ZERO_WIDTH_SPACE to indicate to a user agent a position to break a run of characters. This is typically in a long signature, between the method name and left parenthesis.

As a character, this appears in the displayed output, and is included if a user copies a signature for use elsewhere. The resulting "unusual" large hex Unicode character can cause surprise and confusion.

An alternative to consider would be to use the HTML `<wbr>` element.

As an added benefit `<wbr>` is a shorter string than `&#8203;` so the HTML files will also be smaller as a result.