[MM-29845] Add a new handler to allow authentication via CWS API Key (#16319)

* Add a new handler to allow authentication via CWS API Key

* Make error better

* Add tests and cases for new handler functions

* Move some code around

* Add test for GetCloudSession function

* unset the env after test completion

* Remove white space

* Change Info to Warn

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/session.go

@@ -25,6 +25,7 @@ const (
 	SESSION_PROP_IS_BOT               = "is_bot"
 	SESSION_PROP_IS_BOT_VALUE         = "true"
 	SESSION_TYPE_USER_ACCESS_TOKEN    = "UserAccessToken"
+	SESSION_TYPE_CLOUD_KEY            = "CloudKey"
 	SESSION_PROP_IS_GUEST             = "is_guest"
 	SESSION_ACTIVITY_TIMEOUT          = 1000 * 60 * 5 // 5 minutes
 	SESSION_USER_ACCESS_TOKEN_EXPIRY  = 100 * 365     // 100 years