Generic CRUD pattern trait for DB services

[ipapandinas]

Instead of having multiple DB services traits for each route, we should implement a generic one following CRUD pattern. For example:

#[async_trait]
pub trait DBService<T, K>: Send + Sync + Clone + 'static 
where
    T: Send + Sync + 'static, 
    K: Send + Sync + 'static,
{
    async fn get_all(&self) -> Result<Vec<T>, reject::Rejection>;
    async fn get_by_id(&self, id: i64) -> Result<Option<T>, reject::Rejection>;
    async fn create(&self, item: K) -> Result<T, reject::Rejection>;
    async fn update(&self, id: i64, item: K) -> Result<T, reject::Rejection>;
    async fn remove(&self, id: i64) -> Result<(), reject::Rejection>;
}