* refactor(medusa): Cleanup + fix
* styles(medusa): Lint
* refactor(medusa): Finalize cleanup
* feat(medusa): Prefer the usage of bulk operations instead of sequential/conccurent operations
* feat(medusa): Improve cart service
* refactor(medusa): Explicitly specifying protected methods when needed as well as enfore the usage of the local transactionManager_ in those methods
* tests(medusa): Fix tests according to the new changes
* feat(medusa): Cleanup after rebase
* test(medusa): Fix cart service tests