[NavMesh Pathfinding] Find paths near obstacles

[D8H]

Description

• A feature request on this feature: NavMesh pathfinding behavior #2856
• When the origin or the target is on an obstacle or within the margin, no path is found.

Functional solution

• The pathfinding could try to find a path to the nearest location.
• Add a parameter allow the target everywhere or just outside the obstacles.

Technical solution

• The pathfinding could use something like RBush to look for the the polygons at the origin and target locations.
• The code that handles it is in the pathfinding library. A new method could be added in the library to give it directly the origin and target polygons of the NavMesh.