Feature/improve cleanup 1d3d couplingmanager

Several smaller cleanups and improvements in the 1d3d coupling manager

• Use GridIndex
• Optimise point source data performance by not using maps
• Optimise integration point source by only storing a single element index
• Add possibility to distribute integration point source with box trial functions
• Rename fvGridGeometry -> gridGeometry

Affects only the test with the label multidomain_embedded