feat(medusa, medusa-js, medusa-react): Implement Sales Channel list (#1815)

**What**
Support sales channel list in medusa, medusa-js and medusa-react

**How**

By implementing a new endpoint and the associated service method as well as the repository methods.

Medusa-js new list method in the resource

Medusa-react new hook in the queries

**Tests**

Endpoint test
Service test
Integration test
Hook tests

Fixes CORE-280

packages/medusa-react/test/hooks/admin/sales-channels/queries.test.ts

@@ -1,10 +1,10 @@
-import { useAdminSalesChannel } from "../../../../src"
+import { useAdminSalesChannel, useAdminSalesChannels } from "../../../../src"
 import { renderHook } from "@testing-library/react-hooks"
 import { fixtures } from "../../../../mocks/data"
 import { createWrapper } from "../../../utils"
 
 describe("useAdminSalesChannel hook", () => {
-  test("returns a product", async () => {
+  test("returns a sales channel", async () => {
     const salesChannel = fixtures.get("sales_channel")
     const { result, waitFor } = renderHook(
       () => useAdminSalesChannel(salesChannel.id),
@@ -19,3 +19,17 @@ describe("useAdminSalesChannel hook", () => {
     expect(result.current.sales_channel).toEqual(salesChannel)
   })
 })
+
+describe("useAdminSalesChannels hook", () => {
+  test("returns a list of sales channels", async () => {
+    const salesChannels = fixtures.get("sales_channels")
+    const { result, waitFor } = renderHook(() => useAdminSalesChannels(), {
+      wrapper: createWrapper(),
+    })
+
+    await waitFor(() => result.current.isSuccess)
+
+    expect(result.current.response.status).toEqual(200)
+    expect(result.current.sales_channels).toEqual(salesChannels)
+  })
+})