Simple buisness logic for pet-manager

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It requires a couple of business logic features if we don't go further. I'm open to any suggestions!

1. Create a simple POJO (id, timestamp, command(enum), description).
2. Create a CRUD controller.
3. Create a DTO object that contains only (id, command(enum)).
4. Create a service that maintains a list of objects (DB will be in the next story). DAO.
5. Set up Postmen collection with CRUD operations.

Resources:

1. DAO - https://www.baeldung.com/java-dao-pattern
2. DTO - https://www.baeldung.com/java-dto-pattern
3. POJO vs DTO - https://www.baeldung.com/java-pojo-javabeans-dto-vo
4. DTO - https://www.baeldung.com/java-dto-pattern

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