chore(storybook): upgrade to 8.4.5

[florian-sanders-cc]

What does this PR do?

• Upgrades Storybook to 8.4.5
• Adapts to the Storybook bug introduced recently:
  • we used to rely on staticDirs to copy CSS files from node_modules to a public styles directory,
  • this was necessary because docs pages needed CSS from some npm packages (github-markdown for the converted markdown global styling & highlight for <pre> & <code> content),
  • the staticDirs was actually not supposed to work for this usecase because it was supposed to only handle directories and not files (see #29576),
  • it turns out you only need to import your css files in .storybook/preview.js and the builder will:
    • process / optimize the CSS file,
    • generate the proper <link rel="stylesheet"> tag in the Story iframe HTML.

How to review?

• Check random storybook pages from the preview (try to check at least 1 doc, 1 component story, etc.),
• Do the same running storybook locally,
• 1 reviewer should be enough.

[github-actions]

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[pdesoyres-cc]

I checked the code and have nothing to say about it apart from the fact that I like the removal of the hack around CSS.

I tested several docs and stories and I didn't see anything broken

I just noticed a little mistake: the commit is talking about an upgrade to version 8.4.4 instead of 8.4.5.

Apart from that, LGTM. Well done Florian

[github-actions]

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