Add "What's New" to the web client update banner

The web client has a banner, “A Plex Media Server update is available…” There are links to “Download now” or “Skip this version”. I would like there to be a link that opens the “What’s new” popup.

Currently that popup can be accessed by going to the Settings for the Server, but that is 4-5 clicks away.

Early 2021 clean-up: implemented