Fix callout spacing for new callouts (sans icons)

[wustep]

Description

See issue #565

Notion recently introduced two changes to callouts:

• There is no longer a forced text title and instead we just have block contents, allowing blocks like <h1> at the top of a callout.
• You can remove the icon from the callout entirely (this was me 😉).

This led to some minor visual issues with react-notion-x.

In this PR, we:

• Remove the icon entirely when it is missing
• Removes the top padding/margins on the callout text's first child.

Notion Test Page ID

1425cb08cf2c80efb771e6010d8dac21

Notion

Main [before change]
https://react-notion-x-demo.transitivebullsh.it/1425cb08cf2c80efb771e6010d8dac21

After change

Old callouts are fine too

(Note: there seems to be a funny bug with adjacent headings being rendered on the same line 😛. This is not addressed in this PR.)

[vercel]

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Name	Status	Preview	Updated (UTC)
react-notion-x	✅ Ready (Inspect)	Visit Preview	Nov 18, 2024 9:15am
react-notion-x-minimal-demo	✅ Ready (Inspect)	Visit Preview	Nov 18, 2024 9:15am

[transitive-bullshit]

Thanks @wustep 🙏