Implement Metadata-Based Layer Discovery and Association for Tree Model Nodes in QGIS

[timlinux]

This task involves creating a mechanism to automatically discover and associate map layers in QGIS with nodes (indicators, factors, dimensions) in the tree model by analyzing the metadata of each layer loaded in QGIS. The process includes:

1. Metadata Scanning: Scan metadata of each layer loaded in QGIS for relevant keywords or categories that match node names in the tree model.
2. Association Logic: Automatically associate the matching layer with the corresponding node as the primary layer.
3. Setting Default Layer: In the QGIS map layer combo box, set the discovered layer as the default.
4. Error Handling: Provide feedback when no matching layers are found or if multiple matches are detected.