Move database connection utils to dbconn
Created by: asdine
There currently are two separate connection helpers, using two different PG drivers.
This unifies database connection helpers and merges them into one single package.
dbconn
is now the only package responsible for connecting to the database and database migrations.
dbutil
is now only responsible for generic helpers.
Note: This relies on adding support for driver.ConnBeginTx on the sqlhooks package https://github.com/gchaincl/sqlhooks/pull/33
Fixes #16586