## Description
* After importing the block into a page, the browser does not have the
updated values on the on page load actions.
* The newly created actions, actionCollections which needs to run after
adding the block to canvas are missing.
* This is because unlike normal flow, here the server fetch the Block
data from DSL and then has to import it and send the widget DSL from the
block to client so that the widgets are visible on the canvas. Hence
adding this to response to make the experience same as other widgets
Fixes#31992
## Automation
/ok-to-test tags="tag.ImportExport"
### 🔍 Cypress test results
<!-- This is an auto-generated comment: Cypress test results -->
> [!IMPORTANT]
> Workflow run:
<https://github.com/appsmithorg/appsmith/actions/runs/8379501235>
> Commit: `a6599b14c4027179f79a31b3d6a8e1dad1cc96f0`
> Cypress dashboard url: <a
href="https://internal.appsmith.com/app/cypress-dashboard/rundetails-65890b3c81d7400d08fa9ee5?branch=master&workflowId=8379501235&attempt=1"
target="_blank">Click here!</a>
> All cypress tests have passed 🎉🎉🎉
<!-- end of auto-generated comment: Cypress test results -->
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **New Features**
- Introduced a new data structure to enhance building block imports,
including widget layouts and onPageLoad actions.
- **Refactor**
- Updated the import functionality to utilize the new data structure for
building blocks, improving the handling of layout data and onPageLoad
actions.
- **Tests**
- Modified unit tests to align with the new data structure for building
block imports, ensuring compatibility and correctness.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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