Refactor Snippet Editor permalink Logic

[abotteram]

Please give us a description of what happened.

See Yoast/wordpress-seo#3514

This is the second step to fixing the above issue. Implement the API introduced in #780 into the SnippetEditor. We will need to create a new branch to merge this into because it will change the current SnippetEditor API. Implementing this new API into wordpress-seo will be a new issue.

Specs:
The snippet editor should take a urlStructure and a urlParts array, just like in the aforementioned API. When either of these props change, the new URL should be built and stored in state. So preferably not on every render call.

• The baseURL and url props should be removed.
• The logic that creates the breadcrumbs should not have to change.

Technical info

• yoast-components version:

Requires #780