chore(): Reorganize modules (#7210)

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

packages/modules/customer/src/models/customer-group.ts

@@ -0,0 +1,70 @@
+import { DAL } from "@medusajs/types"
+import { DALUtils, Searchable, generateEntityId } from "@medusajs/utils"
+import {
+  BeforeCreate,
+  Entity,
+  OnInit,
+  OptionalProps,
+  PrimaryKey,
+  Property,
+  ManyToMany,
+  Collection,
+  Filter,
+} from "@mikro-orm/core"
+import Customer from "./customer"
+import CustomerGroupCustomer from "./customer-group-customer"
+
+type OptionalGroupProps = DAL.SoftDeletableEntityDateColumns // TODO: To be revisited when more clear
+
+@Entity({ tableName: "customer_group" })
+@Filter(DALUtils.mikroOrmSoftDeletableFilterOptions)
+export default class CustomerGroup {
+  [OptionalProps]: OptionalGroupProps
+
+  @PrimaryKey({ columnType: "text" })
+  id!: string
+
+  @Searchable()
+  @Property({ columnType: "text", nullable: true })
+  name: string | null = null
+
+  @ManyToMany({
+    entity: () => Customer,
+    pivotEntity: () => CustomerGroupCustomer,
+  })
+  customers = new Collection<Customer>(this)
+
+  @Property({ columnType: "jsonb", nullable: true })
+  metadata: Record<string, unknown> | null = null
+
+  @Property({ columnType: "text", nullable: true })
+  created_by: string | null = null
+
+  @Property({
+    onCreate: () => new Date(),
+    columnType: "timestamptz",
+    defaultRaw: "now()",
+  })
+  created_at: Date
+
+  @Property({
+    onCreate: () => new Date(),
+    onUpdate: () => new Date(),
+    columnType: "timestamptz",
+    defaultRaw: "now()",
+  })
+  updated_at: Date
+
+  @Property({ columnType: "timestamptz", nullable: true })
+  deleted_at: Date | null = null
+
+  @BeforeCreate()
+  onCreate() {
+    this.id = generateEntityId(this.id, "cusgroup")
+  }
+
+  @OnInit()
+  onInit() {
+    this.id = generateEntityId(this.id, "cusgroup")
+  }
+}