fix: Tax region + rates clean up (#9279)

What
- Require `code` on Tax Rates
- Update dashboard to account for non-nullable code on Tax Rates

- Include `automatic_taxes` in API Route response

Closes CC-524 CC-525

integration-tests/modules/__tests__/tax/admin/tax.spec.ts

@@ -234,6 +234,29 @@ medusaIntegrationTestRunner({
         )
       })
 
+      it("should fail to create a tax rate without a code", async () => {
+        const errResponse = await api
+          .post(
+            `/admin/tax-regions`,
+            {
+              country_code: "us",
+              default_tax_rate: {
+                rate: 2,
+                name: "default rate",
+              },
+            },
+            adminHeaders
+          )
+          .catch((e) => e)
+
+        expect(errResponse.response.status).toEqual(400)
+        expect(errResponse.response.data).toEqual({
+          message:
+            "Invalid request: Field 'default_tax_rate, code' is required",
+          type: "invalid_data",
+        })
+      })
+
       it("can create a tax rate and update it", async () => {
         const regionRes = await api.post(
           `/admin/tax-regions`,