Redo Zui Installation videos & update Filesystem Paths doc

[philrz]

The videos at https://zui.brimdata.io/docs/Installation are still mostly ok, but need some updates to reflect the new "Zui" name and also show the "per-machine" install option that was added in #2686. On that latter point, the Filesystem Paths article also needs an update to reflect the different pathnames on Windows the user may have based on whether they're using a per-user or per-machine install. The videos should also start using the newer volcano graphic.

[philrz]

New install videos are now at https://zui.brimdata.io/docs/Installation and the updated filesystem paths article is at https://zui.brimdata.io/docs/support/Filesystem-Paths.