Forward name attributes are not supported in flow

**Describe the bug**
I am not sure whether this is known or was reported before. When there are pipes(XmlIfPipe, IsXmlPipe..) with thenForwardName and elseForwardName attributes are used instead of actual Forward elements frank-flow creates just one arrow to the next pipe in the pipeline.

**Reporter**
Ali

**Expected behavior**
I would expect to have two arrows to the referenced pipes in the attributes.

Start by reproducing a flow containing XmlIfPipe or IsXmlPipe with thenForwardName and elseForwardName instead of Forward elements, then trace how those attributes are interpreted in the flow editor. Done means the resulting graph shows arrows to both referenced pipes rather than only the next pipe in the pipeline.

Written by the indexing model from the issue text.