Membership Level Block - with Individual Level Parts

[JarrydLong]

All Submissions:

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

Changes proposed in this Pull Request:

Allows you to add a Membership Level Block with separate level parts including Level name, description, price, expiration text and checkout button.

How to test the changes in this Pull Request:

1. Edit a page and add the Single Level Block
2. Select a Level that the block should display

Other information:

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

Changelog entry

New Feature: Implemented a new Membership Level block