Extract Database Methods in InserterTrait and UpdaterTrait

## Extract database methods in InserterTrait and UpdaterTrait so that overloading insert and update methods requires less code duplication

### Acceptance Criteria
1. InserterTrait and UpdaterTrait have methods extracted which strictly perform the database interaction.
1. The methods take an entity and the values that are to be set on that entity in the database.
1. Logical flow of `insert` and `update` methods is not changed, with the convenient effect that backward compatibility is maintained.