Presets: Support recursive addon imports

Currently, addons can reference other addons by name. For example, addon-essentials has the following structure:

export const addons = async (existing) => ([...existing, '@storybook/addon-actions', ...]);

This matches how users configure addons in their .storybook/main.js file. However, it presents problems when it comes to package management / module resolution / hoisting, since the dependencies are implicit. If instead we supported the ability to reference other addons directly, this would mean that an addon’s dependencies are explicit and we wouldn’t have to play any games with module resolution.

We should update Storybook’s preset mechanism and port existing addons to this structure:

export const addons = async (existing) => ([...existing, await import('@storybook/addon-actions'), ...]);

We wouldn’t need to force users to adopt this in main.js, but it would be useful for addons that make use of other addons (e.g. addon-essentials).

[shilman]

@IanVS @tmeasday is it correct that we won’t pursue this issue now that @IanVS 's PR has been merged/released, and if we do enhance it, it will be a different approach with an addons field in preview.js? In other words, should I leave this closed?

[tmeasday]

That sounds right to me @shilman