chore(): Reorganize modules (#7210)

**What**
Move all modules to the modules directory

packages/modules/customer/src/joiner-config.ts

@@ -0,0 +1,49 @@
+import { Modules } from "@medusajs/modules-sdk"
+import { ModuleJoinerConfig } from "@medusajs/types"
+import { MapToConfig } from "@medusajs/utils"
+import { Address, Customer, CustomerGroup } from "@models"
+
+export const LinkableKeys = {
+  customer_id: Customer.name,
+  customer_group_id: CustomerGroup.name,
+  customer_address_id: Address.name,
+}
+
+const entityLinkableKeysMap: MapToConfig = {}
+Object.entries(LinkableKeys).forEach(([key, value]) => {
+  entityLinkableKeysMap[value] ??= []
+  entityLinkableKeysMap[value].push({
+    mapTo: key,
+    valueFrom: key.split("_").pop()!,
+  })
+})
+
+export const entityNameToLinkableKeysMap: MapToConfig = entityLinkableKeysMap
+
+export const joinerConfig: ModuleJoinerConfig = {
+  serviceName: Modules.CUSTOMER,
+  primaryKeys: ["id"],
+  linkableKeys: LinkableKeys,
+  alias: [
+    {
+      name: ["customer", "customers"],
+      args: {
+        entity: Customer.name,
+      },
+    },
+    {
+      name: ["customer_group", "customer_groups"],
+      args: {
+        entity: CustomerGroup.name,
+        methodSuffix: "CustomerGroups",
+      },
+    },
+    {
+      name: ["customer_address", "customer_addresses"],
+      args: {
+        entity: Address.name,
+        methodSuffix: "Addresses",
+      },
+    },
+  ],
+}