Debug Challenge - DO NOT MERGE

[dparker1005]

All Submissions:

• Have you followed the Contributing guidelines?
• 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:

Shows administrator the subscription price being paid for a group account when managing a group.

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.

[dparker1005]

Answers

Functional Issues:

• Line 400: esc_html_e() => esc_html__ if there is no subscription.
  
• Lines 400 and 424: Incorrect text domain paid-memberships-pro

Security Issues:

• Line 423: Missing esc_attr()

Fatal Errors:

• Line 399: The PMPro_Subscription class was introduced in PMPro v3.0. We still need backward compatibility for PMPro v2.x.
• Entire function: This function is a callback to a shortcode that runs even if PMPro is inactive. This means that if PMPro is inactive, PMPro-specific functions like pmpro_get_element_class() will cause fatal errors when this shortcode is rendered. This is not only an issue in this PR, but in the existing function.