feat: Add blocks to PageWrapper

[sharmanirudh]

Add feature to get the blocks present in the Document AI JSON response as a Python list of documentai.Document.Page.Block objects, similar to the way to get the paragraphs and lines.

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• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass - I don't know how to configure these. Any help would be really appreciated.
• Code coverage does not decrease (if any source code was changed) - I don't know how to configure and run these. Any help would be really appreciated.
• Appropriate docs were updated (if necessary)

Fixes #106 🦕

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[holtskinner]

Thanks for the contribution!

Please write Unit Tests for your new function

They should go in https://github.com/googleapis/python-documentai-toolbox/blob/main/tests/unit/test_page.py

And make sure that the other unit tests still pass.

[sharmanirudh]

Thanks for the contribution!

Please write Unit Tests for your new function

They should go in https://github.com/googleapis/python-documentai-toolbox/blob/main/tests/unit/test_page.py

And make sure that the other unit tests still pass.

Thanks for your prompt help, I've added the Unit Tests.

[sharmanirudh]

Thanks @holtskinner for your prompt help 🙂