I want to add C++ Double Ended Queue code

#### This issue is about [DE Queue].

- [X] Issue Title is in form `DE Queue[C++]`.
- [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.

No file, test, or entry point is named. Start by inspecting the repository's existing algorithm and data-structure layout and comparable C++ implementations. Done means adding a C++ double-ended queue implementation in the repository's established structure, with any applicable checks or tests passing.

Written by the indexing model from the issue text.