Basilar Artery Bifurcation Aneurysm: Small Wide-Necked Incidental Basilar Artery Bifurcation Aneurysm, Treated with Staged pCONUS1 HPC Implantation and Coil Occlusion; Protrusion of a Coil Loop into the Basilar Artery Bifurcation, Which Prompted the Removal of That Coil Using an Alligator Device