[Enhancement] Add support to choose from existing DB containers

[Utkar5hM]

Currently, there is no support for choosing from existing DB containers when deploying instances. This can be inconvenient and wasteful, as it requires creating new DB containers for each instance, even if there are already existing containers that can be used.

To address this issue, we propose the following tasks:

• Create a new model to handle databases that will have a column for repository.
• Delete DB containers on stop with DB, and only if they are not used by other instances than mentioned.
• Implement DB cleanup on delete repository.
• Keep track of DBs with the newly created model.
• These tasks will enable users to choose from existing DB containers when deploying instances, reducing the need for new containers and improving efficiency.

Tasks completion:

• A new model is created to handle databases with a column for repository.
• DB containers are deleted on stop with DB, and only if they are not used by other instances than mentioned.
• DB cleanup is implemented on delete repository.
• DBs are tracked with the newly created model.
• Users can choose from existing DB containers when deploying instances.
• The code is tested and works as expected.