fix: adding property setter for table constraints, #1990

[lkhagvadorj-amp]

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Fixes #1990 🦕

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Overview

This pull request introduces enhancements to the google/cloud/bigquery/table.py file by adding setter methods and conversion functions. Additionally, a new unit test is added to ensure the functionality of the new setter method.

Enhancements to google/cloud/bigquery/table.py:

• Added a setter method for table_constraints to allow setting primary key and foreign key information.
• Added to_api_repr method to the ForeignKey class to return a dictionary representation of the object.
• Added to_api_repr method to the TableConstraints class to return a dictionary representation of the object.

Unit tests:

• Added a test for the table_constraints property setter to ensure it correctly updates the table properties.

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[Linchin]

Thank you @lkhagvadorj-amp for making the contribution! The PR looks great, but could you do the following things so we can merge it:

1. sign the CLA because it's part of the legal requirements
2. add some unit tests: unit tests for both to_api_repr() methods, and more test cases for the setter, for 100% test coverage
3. add a system test for this property

Thanks again and happy holidays!

[lkhagvadorj-amp]

@Linchin
Hi

Happy to contribute and thank you for the initial review!

I’ve pushed the testing changes—would be grateful if you could review them again.

Happy holidays!

[Linchin]

We also need to add a unit test for this branch.

[Linchin]

Thank you @lkhagvadorj-amp, I ran the test again, but it seems we need to fix several tests. I'm sorry that I have to trigger the presubmit tests manually, but you can run the system test locally by pytest tests/system/test_client.py, the lint test by nox -s lint, and mypy_samples test by nox -s mypy_samples. (You can install nox by pip install nox.)