add data.preview viewData config liveShare features

[RandomFractals]

my idea for #liveShare of #dataPreview ext. is simple: devs and data scientists scoping supported data files for their data vizes should be able to exchange data view configs with grid/charts options when looking at data for their apps in a live share session to sync data views.

see this chat with @lostintangent for more info:

https://twitter.com/TarasNovak/status/1133452018377482240

[RandomFractals]

see https://github.com/aaronpowell/vscode-profile-switcher/pull/4 for liveshare in vscode api and some implementation ideas for this part