go: use sqlc for all db calls

[Forfold]

The purpose of this issue is to track migrating all prepared DB statements to use sqlc.

How to migrate a prepared statement to `sqlc`

1. Create a file named queries.sql in the directory you are working in
2. Add your query with the comment above declaring its name and return type. Here are three examples: a query returning one row, a query returning multiple rows, and a query updating rows (and not returning anything):

-- name: AlertHasEPState :one
SELECT
  EXISTS (
      SELECT
          1
      FROM
          escalation_policy_state
      WHERE
          alert_id = $1) AS has_ep_state;

-- name: AlertFeedback :many
SELECT
  alert_id,
  noise_reason
FROM
  alert_feedback
WHERE
  alert_id = ANY($1::int[]);

-- name: SetAlertFeedback :exec
INSERT INTO alert_feedback(alert_id, noise_reason)
  VALUES ($1, $2)
ON CONFLICT (alert_id)
  DO UPDATE SET
      noise_reason = $2
  WHERE
      alert_feedback.alert_id = $1;

3. Generate your queries to call with gadb: make generate
4. Call your query:

row, err := gadb.New(tx).AlertHasEPState(ctx, int64(id))
  	if err != nil {
  		return fmt.Errorf("check ep state: %w", err)
  	}

Notes:

• Sometimes you'll need to cast types (e.g., $1::int but then it loses the name, so if there's multiple args it will be things like Column1 so it's better to switch to named args, in that case, @id::int
• If your query is executing (insert or update) but still returning rows, be sure to tag it as :one or :many, respectively. If it doesn't return anything, tag it as :exec after the name.

Files with prepared db statements to migrate to sqlc:

• alert/store.go
• alert/alerlog/store.go
• alert/alertmetrics/store.go
• auth/handler.go
• auth/basic/db.go
• auth/nonce/store.go
• config/store.go
• engine/backend.go
• engine/cleanupmanager/db.go
• engine/compatmanager/db.go
• engine/escalationmanager/db.go
• engine/escalationmanager/update.go
• engine/heartbeatmanager/db.go
• engine/message/db.go
• engine/metricsmanager/db.go
• engine/npcyclemanager/db.go
• engine/processinglock/conn.go
• engine/processinglock/lock.go
• engine/rotationmanager/db.go
• engine/schedulemanager/db.go
• engine/verifymanager/db.go
• engine/verifymanager/update.go
• escalation/store.go
• gadb/db.go
• heartbeat/store.go
• integrationkey/store.go
• keyring/store.go
• label/store.go
• limit/store.go
• notice/store.go
• notification/store.go
• notification/twilio/dbsms.go
• notificationchannel/store.go
• oncall/store.go
• override/store.go
• schedule/store.go
• schedule/rotation/store.go
• schedule/rule/store.go
• service/store.go
• user/store.go
• user/contactmethod/store.go
• user/favorite/store.go
• user/notificationrule/store.go
• util/sqlprepare.go