Auto migration: Detect .stories.mdx and @storybook/mdx1-csf usage

[yannbf]

The work done in #25182 removed support for *.stories.mdx and the CSF in MDX format, which is impactful for a few users:

• *.stories.mdx stories should be migrated to new *.mdx format (there is a codemod already here)
• usage of the legacyMdx1 feature in main.js should be removed

export default {
  features: {
    legacyMdx1: true,
  },
};

• @storybook/mdx1-csf should be uninstalled
• jsxOptions (addon option from addon-docs) should be removed (though I'm not sure if there's more to it)
• link https://storybook.js.org/docs/7.6/migration-guide

[ndelangen]

@yannbf @valentinpalkovic @shilman any idea on how to actually implement this:

jsxOptions (addon option from addon-docs) should be removed (though I'm not sure if there's more to it)

Are we sure we want to spend the time, and add the complexity to our codebase for this?
AFAICS this option doesn't do anything anymore.

[yannbf]

@ndelangen I unfortunately do not have a lot of context on usage of the jsxOptions. All I know that it was part of mdx1 and that won't exist anymore because we removed it.