SyntheticBoundaryNode tag corner cases for Raw Atlas

[matthieun]

There are some corner cases related to SyntheticBoundaryNodeTag assignment that are handled in the legacy OsmPbfProcessor.

• Walk ways outside boundaries
  • The Edges that span out of a country and do not belong to any other country need to be added to the current country build, as long as they are connected to at least one Edge that is inside the boundary.
  • That should cover for bridges and ferries that span outside of country boundaries.
• Add synthetic boundary node tags at the end of those ways
  • All the above mentioned ways that are added end at some node. That node needs to have a synthetic boundary node tag, as that tag is not added right at the boundary.
  • Avoid the bug fixed here: Remove false positive existing boundary tag #71

[matthieun]

Sub-task of #17