In the current version of Jetpack, you can go to Jetpack > Settings in your dashboard and activate or deactivate all modules at once, thanks to the bulk editing options.

In Jetpack 4.3, you have 2 options:

1. You can disable JavaScript in your browser while visiting the new Jetpack dashboard, and the old Settings screen will appear.
2. You can go to the old settings URL if you have it bookmarked (/wp-admin/admin.php?page=jetpack_modules).

It would be nice to offer a quick access to those bulk editing options in the new Jetpack interface.

I can think of 2 ways to quickly add that option back, as a work-around:

1. Add a link to the old settings URL somewhere in the Jetpack dashboard; in the footer, for example.
2. Once the search feature will be available, include bulk editing capabilities to the search results page; one could search for "Appearance", and be able to activate / deactivate all Appearance related modules; A search for "all" could allow you to edit all modules at once.