feat: filter for settings access

[adekbadek]

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Adds filtering of admin panel access. This will be used by upcoming changes in the Newspack Plugin, which will introduce granular capabilities management.

How to test the changes in this Pull Request:

1. There should be no functional changes for end users, this is a backend feature. Verify that Newspack Advertising wizard can still be accessed as an admin* user

* a user with manage_options capability

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 ran tests with your changes locally?

[chickenn00dle]

LGTM 👍

[matticbot]

🎉 This PR is included in version 1.46.0-alpha.1 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀

[matticbot]

🎉 This PR is included in version 1.46.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀