Fix missing/pending blocks

[janniks]

The #52 fix introduced some new problems with missing blocks:

• https://github.com/splitbee/notion-api-worker/issues/57
• https://github.com/splitbee/react-notion/issues/79;

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The #52 fix only fetched potential blocks from the page block but ignored other content of child blocks → e.g. the react-tester page toggle block doesn't contain its child content

The original page logic fetched potential blocks by going over content of non-page blocks.

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In this PR:

• https://github.com/splitbee/notion-api-worker/pull/52/commits/bf8c9c50b8ff75eda153b1efa6b2e121c9f4b08c is reverted
• new logic is added that keeps both the current page content blocks and non-page content blocks

[tobiaslins]

Thank you @janniks :) Just deployed the fix

[janniks]

Thanks 🙏