Add support for ignoreEntities to forbid teleport to some areas

[vincentfretin]

Add support for ignoreEntities similar to aframe-cursor-teleport to ignore some meshes to teleport to. This is mainly to have the same teleport area as with simple-navmesh-constraint were you can exclude meshes by adding navmesh-hole class to it, see https://github.com/AdaRoseCannon/aframe-xr-boilerplate#simple-navmesh-constraintjs