Fix TurboSnap support for Storybook in a subdirectory (part 2)

[yngvebn]

This PR fixes a bug related to situations where Chromatic (Turbosnap enabled) fails with the error "Did not find any CSF globs in preview-stats.json" (#530 and #486 - not sure if these are caused by the same error)

The error occurs if you're using Storybook 6.4 and pass in configDir as something else than '.' to Chromatic, and the reason stems from this array of predefined paths:

const storiesEntryFiles = [
    // v6 store (SB <= 6.3)
    `${storybookDir}/generated-stories-entry.js`,
    // v6 store with root as config dir (or SB 6.4)
    `generated-stories-entry.js`,
    // v6 store with .cjs extension (SB 6.5)
    'generated-stories-entry.cjs',
    // v7 store (SB >= 6.4)
    `storybook-stories.js`,
    // vite builder
    `/virtual:/@storybook/builder-vite/vite-app.js`,
];

In this case, storybookDir will be resolved as a combination of baseDir + storybookConfigDir whereas the rest are not. This fix ensures the storiesEntryFiles respects both storybookBaseDir and storybookConfigDir

[tmeasday]

This changes makes sense to me. We should always be looking for paths relative to the project root.

Thanks @yngvebn. @ghengeveld I'll let you merge if you agree + release 👍

[ghengeveld]

Thanks. This was similar to the work done in #527 but yours is actually better because it normalizes all entry file paths, making it more robust and future-proof. I ended up using a bit from both PRs and cleaning up a couple things. Nice work!

[ghengeveld]

Released in 6.5.2.