DSE: Remove the (now) superfluous inputProject ref

• The inputProject reference is no longer needed as we have model snapshots that freeze the import state. Originally, this reference was intended to host a copy of the imported FileProject state at the time of importing.
• The File Project can simply be accessed by ascending the containment hierarchy.
• The referenced caused model corruption when exporting a found solution from the DSE: The FileProject id was reset to some id > 0 that is a duplicate of some random model element. Loading such a model violated basic assumptions and ambiguous references.

Issue-Ref: 3742 Issue-Url: https://af3-developer.fortiss.org/issues/3742 Signed-off-by: Alexander Diewald diewald@fortiss.org