Manage version configurations client versions (#7220)

* Add config values for client versions. Return client versions in ping response.

* Manage client version through System Console.

* Added client versions to diagnostics

* Added translations messages en.json file.

* Hide Client Versions on System Console.

config/default.json

@@ -76,6 +76,14 @@
         "MaxNotificationsPerChannel": 1000,
         "TeammateNameDisplay": "username"
     },
+    "ClientRequirements": {
+        "AndroidLatestVersion": "",
+        "AndroidMinVersion": "",
+        "DesktopLatestVersion": "",
+        "DesktopMinVersion": "",
+        "IosLatestVersion": "",
+        "IosMinVersion": ""
+    },
     "SqlSettings": {
         "DriverName": "mysql",
         "DataSource": "mmuser:mostest@tcp(dockerhost:3306)/mattermost_test?charset=utf8mb4,utf8&readTimeout=30s&writeTimeout=30s",