Favorites support for SSE

[Gavin Mogan]

I'm slowly upgrading my really old html5 notifier plugin, giving it some love, and switching from a custom polling to the sse-gateway plugin

Does it make sense to create a PR for Favorites Plugin to optionally support SSE events? or SSE to optionally support favorites? Or brand new plugin

I kinda feel like best place is favs, but not sure.

Gavin

PS, would love someone who has npm access to merge https://github.com/jenkinsci/sse-gateway-plugin/pull/44 deployed to npm