LPS-33007

LPS-33568 Obtain palette items for the Application Display Templates

The classPK parameter of getTemplateVariablesMap() is not used yet in the implementations included in this pull, but it will be used in upcoming implementations.

I didn't include javadocs for the new methods yet, because I prefer to wait until all implementations are done to make sure it's accurate.

I have hardcoded the Javadoc URL in a JSP. I wasn't sure if a portal.properties property was better. Let me know if you think so.