addon-viewport: cycling through viewports with keyboard shortcuts

[kaelig]

Is your feature request related to a problem? Please describe
I often switch between viewports and it requires a lot of clicking around.

Describe the solution you'd like
Cycling through the viewports like so would be a nice time saver:

• next viewport: V
• previous viewport: shift + V

Describe alternatives you've considered

• A custom addon
• A Chrome extension that adds this functionality

Are you able to assist to bring the feature to reality?
Happy to help reviewing a PR!

Related: #9073

[Dschungelabenteuer]

Okay, I'm jumping in! I'd like to give it a try @shilman, can't assure I'll be doing good though, this will likely require some feedback ☺

[jeremyzilar]

This would be very helpful 🎉

[shilman]

Whoopee!! I just released https://github.com/storybookjs/storybook/releases/tag/v6.3.0-alpha.15 containing PR #14658 that references this issue. Upgrade today to the @next NPM tag to try it out!

npx sb upgrade --prerelease

Closing this issue. Please re-open if you think there's still more to do.