feat(region): Add admin region get + list endpoints (#6322)

**What**
Add `GET /admin/regions`
Add `GET /admin/regions/:id`

Blocked by #6320 

Co-authored-by: Adrien de Peretti <25098370+adrien2p@users.noreply.github.com>

integration-tests/environment-helpers/use-db.js

@@ -11,6 +11,7 @@ const { dropDatabase } = require("pg-god")
 const { DataSource } = require("typeorm")
 const dbFactory = require("./use-template-db")
 const { ContainerRegistrationKeys } = require("@medusajs/utils")
+const { migrateMedusaApp } = require("@medusajs/medusa/dist/loaders/medusa-app")
 
 const DB_HOST = process.env.DB_HOST
 const DB_USERNAME = process.env.DB_USERNAME
@@ -155,35 +156,26 @@ module.exports = {
       const featureFlagLoader =
         require("@medusajs/medusa/dist/loaders/feature-flags").default
 
-      const medusaAppLoader =
-        require("@medusajs/medusa/dist/loaders/medusa-app").default
-
       const container = createMedusaContainer()
 
       const featureFlagRouter = await featureFlagLoader(configModule)
 
+      const pgConnection = await pgConnectionLoader({ configModule, container })
+
       container.register({
         [ContainerRegistrationKeys.CONFIG_MODULE]: asValue(configModule),
         [ContainerRegistrationKeys.LOGGER]: asValue(console),
         [ContainerRegistrationKeys.MANAGER]: asValue(dbDataSource.manager),
+        [ContainerRegistrationKeys.PG_CONNECTION]: asValue(pgConnection),
         featureFlagRouter: asValue(featureFlagRouter),
       })
 
-      const pgConnection = await pgConnectionLoader({ configModule, container })
       instance.setPgConnection(pgConnection)
 
-      const { runMigrations } = await medusaAppLoader(
+      await migrateMedusaApp(
         { configModule, container },
         { registerInContainer: false }
       )
-
-      const options = {
-        database: {
-          clientUrl: DB_URL,
-          connection: pgConnection,
-        },
-      }
-      await runMigrations(options)
     }
 
     return dbDataSource