Tweaks to showing new version available

- Added frontend translation for english
- Moved frontend api logic to hook and backend api space
- Added swagger schema for the new api endpoint
- Moved backend logic to its own internal file
- Added user agent header to github api check
- Added cypress integration test for version check api
- Added a memory cache item from github check to avoid hitting it too
  much

backend/schema/swagger.json

@@ -293,6 +293,11 @@
 				"$ref": "./paths/tokens/post.json"
 			}
 		},
+		"/version/check": {
+			"get": {
+				"$ref": "./paths/version/check/get.json"
+			}
+		},
 		"/users": {
 			"get": {
 				"$ref": "./paths/users/get.json"