Add: WPAcceptance testing

[dinhtungdu]

Description of the Change

Add acceptance testing using 10up/wpacceptance.

Alternate Designs

n/a

Benefits

Give us more confidence when shipping releases.

Possible Drawbacks

n/a

Verification Process

See the CI passed.

Checklist:

• [x] I have read the CONTRIBUTING document.
• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have added tests to cover my change.
• [x] All new and existing tests passed.

Applicable Issues

Changelog Entry

[jeffpaul]

@dinhtungdu the block on this PR from #36 should be gone now that 36 has been merged in

[dinhtungdu]

@jeffpaul Yes, working on this to add more test cases

[dinhtungdu]

@jeffpaul The test case for reordering child pages is falling, and it's expected behavior due to #43

[helen]

I am merging this first - the tests will fail on develop, and then after merging #51 and #53 they should pass.