feat: Updates api controllers to use database client.

Sources/DatabaseClient/PurchaseOrders.swift

@@ -2,6 +2,7 @@ import Dependencies
 import DependenciesMacros
 import Fluent
 import SharedModels
+import Vapor
 
 public extension DatabaseClient {
   @DependencyClient
@@ -15,6 +16,9 @@ public extension DatabaseClient {
   }
 }
 
+extension PurchaseOrder: Content {}
+extension PurchaseOrder.Create: Content {}
+
 extension DatabaseClient.PurchaseOrders: TestDependencyKey {
   public static let testValue: DatabaseClient.PurchaseOrders = Self()
 }