Allowed ?formats param in Admin API post+page create/edit requests

no issue

- `?formats` is useful when you want to get `html` back from the Admin API when creating/editing posts, otherwise you're forced to make a following `GET` request

core/server/api/canary/pages.js

@@ -87,6 +87,7 @@ module.exports = {
         headers: {},
         options: [
             'include',
+            'formats',
             'source'
         ],
         validation: {
@@ -122,6 +123,7 @@ module.exports = {
         options: [
             'include',
             'id',
+            'formats',
             'source',
             'force_rerender',
             // NOTE: only for internal context

core/server/api/canary/posts.js

@@ -89,6 +89,7 @@ module.exports = {
         headers: {},
         options: [
             'include',
+            'formats',
             'source',
             'send_email_when_published'
         ],
@@ -124,6 +125,7 @@ module.exports = {
         options: [
             'include',
             'id',
+            'formats',
             'source',
             'send_email_when_published',
             'force_rerender',