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

Created by: sourcegraph-bot

Notifying subscribers in CODENOTIFY files for diff f96e136470b17a15dd1ad8b040515a1b3a2718b4...46ae5816a32d7c487442fe0ca164c5c966636e50.

Notify	File(s)
@efritz	internal/db/basestore/handle.go internal/db/dbconn/dbconn.go internal/db/dbconn/migration.go internal/db/dbtest/dbtest.go internal/db/dbtesting/dbtesting.go internal/db/dbutil/dbutil.go
@keegancsmith	cmd/gitserver/main.go

Created by: asdine

@ryanslade Not yet, once sqlhooks gets updated I will run integration tests and a migration to check if every is fine

Created by: codecov[bot]

Codecov Report

Merging #17399 (46ae581) into main (f96e136) will increase coverage by 0.01%. The diff coverage is 14.54%.

@@            Coverage Diff             @@
##             main   #17399      +/-   ##
==========================================
+ Coverage   51.87%   51.89%   +0.01%     
==========================================
  Files        1716     1717       +1     
  Lines       85296    85275      -21     
  Branches     7647     7634      -13     
==========================================
+ Hits        44246    44251       +5     
+ Misses      37148    37124      -24     
+ Partials     3902     3900       -2     

Flag	Coverage Δ
go	50.87% <14.54%> (+0.02%)
integration	30.69% <ø> (+<0.01%)
storybook	30.34% <ø> (ø)
typescript	54.35% <ø> (+<0.01%)
unit	34.72% <ø> (ø)

Impacted Files	Coverage Δ
cmd/gitserver/main.go	10.12% <0.00%> (ø)
internal/db/basestore/handle.go	61.53% <0.00%> (ø)
internal/db/dbconn/dbconn.go	11.38% <0.00%> (ø)
internal/db/dbutil/dbutil.go	19.14% <ø> (+2.32%)
internal/db/dbconn/migration.go	17.39% <17.39%> (ø)
client/web/src/nav/StatusMessagesNavItem.tsx	87.71% <0.00%> (+1.75%)
.../internal/codeintel/resolvers/graphql/locations.go	85.56% <0.00%> (+4.12%)