- remove individuals from @angular/* package.json, we don't keep them up-to-date
- switch keys in contributors.json to GitHub handles, seems like a better identifier and lets us grab avatar images from GitHub account
- move emeritus ppl to a new Alumni group (won't yet appear on the site)
- add "lead/mentor" keys so we know who is coordinating work
- add a script that generates an "org chart" graphic
PR Close#28930
Alex Eagle