Check multiple fields to not be empty in the database item entity.
Implemented a small `checkEmptyStringInList` function which checks for an empty string in a vector to not repeat empty checks for each of the field properties and pass all of them instead.
Usage implementation in database items also was added.
Linear task: [[ https://linear.app/comm/issue/ENG-618/confirm-all-fields-are-validated-inside-tunnelbroker-database-entities | ENG-618 ]]