make tax_status more dynamic

[masteradhoc]

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Changes proposed in this Pull Request:

Closes #177 .

How to test the changes in this Pull Request:

1. create new products
2. see if tax_status is randomly generated

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?

Changelog entry

Dynamic assign tax_status for simple and variable products

Enter a summary of all changes on this Pull Request. This will appear in the changelog if accepted.

FOR PR REVIEWER ONLY:

• I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.

[masteradhoc]

@layoutd can you check this PR as well and let me know about potential change requests?

[layoutd]

LGTM