migration script: fix `import Blockly from 'blockly'`

[maribethb]

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Component

migration

Problem

No response

Request

Using import Blockly from 'blockly' has never been recommended or explicitly supported. It won't work when we publish esmodules because we don't have a default export. The migration script should find and change these to import * as Blockly from 'blockly' if possible.

Alternatives considered

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Additional context

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