Bug Fix: Static Edge Type ID Collision in tkgl-smallpedia and tkgl-wikidata

[JuliaGast]

Problem (before PR):
When preprocessing static edges for (tkgl-smallpedia and tkgl-wikidata), the original code assigned static edge type IDs starting from 0.
As a result:

• The first static edge type had the same ID as the first temporal edge type.
• If a static edge was already present in the temporal data, it was assigned two different ids.

This caused inconsistent edge type mappings.

Affected datasets:

• tkgl-smallpedia
• tkgl-wikidata

Fix:

• Edge type IDs are now saved to a .pkl file (similar to how node IDs are stored).
• During preprocessing, static edge types are checked against temporal edge types.
• Any static edge type not already present in the temporal edge types is assigned an ID starting from number_of_temporal_edge_types + 1.
• This ensures that all edge type IDs are globally unique and consistent.

[JuliaGast]

Commit: a9ba593

Previously, when assigning edge IDs for static edges, we started the new IDs at num_edges + 1.
However, because each edge has an inverse edge, the range 0 … (num_edges * 2 - 1) is already occupied.
For example, with num_edges = 100, the valid existing IDs are 0–199. Starting static edges at 101 caused ID collisions.

This update changes the starting ID for new static edges to num_edges * 2, ensuring no overlap with existing edge or inverse-edge IDs.