add back older oncotree versions to dropdown

[sheridancbio]

• older versions added after disabled divider
• versions sorted .. where "visible" attribute now promotes the version to the "above the line" group
• otherwise, versions sorted in reverse chronological order
• cleanup of older code (dropping of dead code) and renaming of variables
• now when entering page, the "selected" attribute of the select options are set according to the html "version" property (or default)

Co-authored-by: Manda Wilson 1458628+mandawilson@users.noreply.github.com