Euler Path and Euler Cycle [Java]

https://www.geeksforgeeks.org/eulerian-path-and-circuit/

#### This issue is about [Algo/DS Name](link to resource for the Algo/DS).

- [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).
- [ ] I ensure that I am not already assigned to 2 or more issues.
- [ ] 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.