Reject port names containing whitespace

[L4co77]

• Add std::isspace check to IsAllowedPortName() to reject port names containing whitespace
• Add IsAllowedPortName() validation in loadSubtreeModel() for TreeNodesModel port names, which previously had no validation
• Update CreatePort error message to mention the whitespace constraint
• Add tests for whitespace rejection in port names

[dsobek]

Makes sense, just going to give this a test in against MoveIt Pro before approving.

For the forward port, could you evaluate if it makes sense to merge the upstream of behaviortree.cpp into our fork? In particular, I realized that some of the validation logic I pointed to you exists in the upstream master branch, and so there might be some duplicate work there. I created a separate issue for this https://github.com/PickNikRobotics/moveit_pro/issues/17640.