Removing role from Edit Member page

[dparker1005]

All Submissions:

• Have you followed the Contributing guideline?
• Does your code follow the WordPress' 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:

We have seen issues on websites where users could have multiple roles or a role that doesn't show in the Roles list on the PMPro Edit Member page. In these situations, saving the Edit Member page for a user could unintentionally change the user's role on the website, potentially adding or removing capabilities for that user. Either of these situations is dangerous and should be avoided.

In the medium term, we would like to add the Role option back, but this needs to be done to ensure compatibility with the various Role setups and plugins available in WordPress. As a "quick fix", this PR removes the role setting entirely. Admins can still edit roles for users from the default Edit User page in core WP.

Other information:

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

Changelog entry

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