CLI: use addon essentials in storybook templates

[yannbf]

Work summary

Make the generated boilerplate from CLI to use addon-essentials and remove the explicit use of @storybook/addon-actions, @storybook/addon-links and @storybook/docs (when applicable) in main.js files.

Essentials will be the easiest way to get started with a high-quality Storybook experience. If all the CLI templates use it and all the tests make sure that it works smoothly with all the existing frameworks, it will be a huge win for users and for Storybook maintenance.

This work is part of #10723 and depends on the E2E setup from #10702

@shilman please chime in about the usage of addons from essentials in the boilerplate! Edit this issue so it's clear for everyone who's reading it.

Where to start

Check all framework templates under generators folder and change them accordingly.

Acceptance criteria

• CLI tests are passing
• E2E tests are passing
• Usage of the addon is proper, aligned with @shilman
• Changes are properly reviewed by some of the members mentioned below

Who to contact

@shilman @yannbf @tooppaaa @ndelangen @gaetanmaisse

[stale]

Hi everyone! Seems like there hasn't been much going on in this issue lately. If there are still questions, comments, or bugs, please feel free to continue the discussion. Unfortunately, we don't have time to get to every issue. We are always open to contributions so please send us a pull request if you would like to help. Inactive issues will be closed after 30 days. Thanks!

[shilman]

Gadzooks!! I just released https://github.com/storybookjs/storybook/releases/tag/v6.0.0-beta.39 containing PR #11282 that references this issue. Upgrade today to try it out!

You can find this prerelease on the @next NPM tag.

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