Import series: redesign an import process to not use series creation page

[php-coder]

Let's create a series at /series/import/request/{id} page instead of redirecting to /series/add with appropriate parameters. There many things that we need only during series import and adding them to series creation could produce errors, will make code complicated, and still won't solve all our requirements.

This issue blocks the following:

• connect import request with created series (Import series: connect import request with created series #700) -- because we need to update request after series creation
• support multiple images (Import series: support multiple images #698) -- because series creation form doesn't support multiple images
• add support for extracting seller info and price (Import series: add support for extracting seller info and price #695) -- because adding sales is completely different process/form