Make tables client policy fetching extensible

[Will-Lo]

Summary

Issue] Briefly discuss the summary of the changes made in this
pull request in 2-3 lines.

TablesClient uses the methods that convert a TableResponseBody to a policy. This PR makes this method to be protected rather than private so that it can be extended if needed.

Changes

• Client-facing API Changes
• Internal API Changes
• Bug Fixes
• New Features
• Performance Improvements
• Code Style
• Refactoring
• Documentation
• Tests

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Testing Done

• Manually Tested on local docker setup. Please include commands ran, and their output.
• Added new tests for the changes made.
• Updated existing tests to reflect the changes made.
• No tests added or updated. Please explain why. If unsure, please feel free to ask for help.
• Some other form of testing like staging or soak time in production. Please explain.

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Additional Information

• Breaking Changes
• Deprecations
• Large PR broken into smaller PRs, and PR plan linked in the description.

For all the boxes checked, include additional details of the changes made in this pull request.