Fix bots being unable to post when personal access tokens are disabled. (#11105)

model/session.go

@@ -19,6 +19,8 @@ const (
 	SESSION_PROP_BROWSER              = "browser"
 	SESSION_PROP_TYPE                 = "type"
 	SESSION_PROP_USER_ACCESS_TOKEN_ID = "user_access_token_id"
+	SESSION_PROP_IS_BOT               = "is_bot"
+	SESSION_PROP_IS_BOT_VALUE         = "true"
 	SESSION_TYPE_USER_ACCESS_TOKEN    = "UserAccessToken"
 	SESSION_ACTIVITY_TIMEOUT          = 1000 * 60 * 5 // 5 minutes
 	SESSION_USER_ACCESS_TOKEN_EXPIRY  = 100 * 365     // 100 years