Doubly linked list [Python]

This issue is about [Doubly linked list](https://en.wikipedia.org/wiki/Doubly_linked_list).

- [x] Issue Title is in form Algo/DS Name [Language].
- [x] I searched or browsed the repo’s other issues to ensure this is not a duplicate.
- [x] This Algo/DS is worth adding to this repository.
- [x] Assign this issue to me (I want to work on this).
- [x] I ensure that I am not already assigned to 2 or more issues.
- [x] I will send my PR only after I'm assigned to this issue by any maintainer.
- [x] I understand that I will be unassigned from this issue if I fail to send a PR for this within a week.

Start by locating existing Python data-structure implementations and their tests or examples to learn the repository's conventions. Confirm the expected doubly linked list operations from neighboring implementations, then ensure the new Python implementation follows those conventions and is covered by the relevant test command, if one exists.

Written by the indexing model from the issue text.