Contextualize database and separate in to modules

[ceyhunsen]

Description

Separates database/common into different files based on the context.

This PR basically moves code to separate modules but it also removes tracing::instruments (because they are useless) and adds some todos regarding to tests etc..

Adds execute_query_with_tx macro that will simplify query execution.

Linked Issues

• Closes Split database/common into submodules #484

[mmtftr]

If you have the time, consider using this (I had written this earlier):

macro_rules! execute_with_tx {
    ($conn:expr, $tx:expr, $query:expr, $method:ident) => {
        match $tx {
            Some(tx) => $query.$method(&mut **tx).await,
            None => $query.$method(&$conn).await,
        }
    };
}


// later
execute_with_tx!(self.connection, tx, query, execute); 

[ceyhunsen]

If you have the time, consider using this (I had written this earlier):

macro_rules! execute_with_tx {
    ($conn:expr, $tx:expr, $query:expr, $method:ident) => {
        match $tx {
            Some(tx) => $query.$method(&mut **tx).await,
            None => $query.$method(&$conn).await,
        }
    };
}


// later
execute_with_tx!(self.connection, tx, query, execute); 

Let me do this in a chain PR and not congest this PR, as there is already too many changes.

[mmtftr]

Thanks a lot for the changes, I think we'll improve in terms of documentation with these small changes

[ceyhunsen]

Let me make this changes in a chain PR again for an easier review experience. We should keep this PR clean from refactors/updates. I made a mistake merging the child PR #488.

After every chain PR is approved, we can merge them one by one. If we don't do this, some changes will be missed by the reviewers.