[MM-10346] CSRF Token Implementation + Tests (#10067)

* CSRF Token Implementation + Tests

Remove debug statements

Implement requested changes

* Fix non-cookie authentication methods stripping auth data from requests

* Fail when CSRF cookie is not returned as part of login

model/session.go

@@ -12,6 +12,7 @@ import (
 const (
 	SESSION_COOKIE_TOKEN              = "MMAUTHTOKEN"
 	SESSION_COOKIE_USER               = "MMUSERID"
+	SESSION_COOKIE_CSRF               = "MMCSRF"
 	SESSION_CACHE_SIZE                = 35000
 	SESSION_PROP_PLATFORM             = "platform"
 	SESSION_PROP_OS                   = "os"