resolve conflicts in igv.js between NIAGADS branch and main and merge

[fossilfriend]

basically shift development to main

[fossilfriend]

synced our igv.js fork

this involved dropping the ROI commits on the master branch. Not concerned b/c IGV implemented their own solution

created NIAGADS from synced master and merged in NIAGADS-2.13.9

Conflicts that needed to be resolved

• index.js exports
• some example .html files
• ROI SVG export
• DOMUtils location

[fossilfriend]

made updates to niagads-igv-webapp (main) to accommodate shift to igv.js master (2.16.0) from 2.13.9

• browser.addToTrackFactory has been deprecated and replaced w/registerTrackClass, see line 84 in IGVBrowser.tsx

TODOS

• [x] bring develop branches in sync w/NIAGADS
• [ ] ROI export to SVG not working; needs to be investigated.