[FEATURE REQUEST] Add a button to update navigation mesh.

[tigres810]

Right now the only way to update a navigation mesh is by moving the navigation bounding box or reloading the project("Correct me if im wrong") a button in any of these two areas I think it would be useful. You can also think of any other places this button could be placed I just thought that these two places are the most accesible for the user. This button would update the navigation mesh represented as green zone in the editor instead of doing what was mentioned at start.