CLI: Automigration for new frameworks

[yannbf]

Issue: N/A

What I did

This PR adds a new automigration to go from older framework format to the new framework format, such as:

from

@storybook/react
@storybook/builder-webpack5
@storybook/manager-webpack5

to

@storybook/react-webpack5

And also make the necessary changes in main.js. There's a limitation currently because the csf-tools don't provide a way to delete keys, so if core was supposed to be deleted, instead it's turned into an empty object.

I tested this in different frameworks and it works great, we can finally have a migration from 6.0 to 7.0 that works right after 👯

A few pics:

Yea, formatting is a slight issue, but we can't do much about it 🤷

How to test

• Is this testable with Jest or Chromatic screenshots?
• Does this need a new example in the kitchen sink apps?
• Does this need an update to the documentation?

If your answer is yes to any of these, please make sure to include it in your PR.

[tmeasday]

Some questions but it looks great!