fix: HAC Clustering - Githubissues

The current state of the Hierarchical agglomerative clustering can be found in the following branch: HAC_drop_BEV

Tests have shown that the clustering leads to feasibility issues (unbound problem) when performing the lopf() with models that are higher resolved (e. g. 300 AC nodes, 43 Gas nodes, 100 snapshots)
The issue seems to be related to the flexibility band of Li Ion nodes which represent the mobility sector. Especially for snapshots where e_nom_min is equal to e_nom_max

Current ToDos:

[ ] Fix problem of missing country codes after AC HAC Clustering (related to changes introduced in )
[ ] Implement HAC for gas sector. Reference: [HAC with gas implemented] (https://github.com/openego/eTraGo/tree/HAC_TimeSeries_based)
[ ] Test if optimization works with HAC clusterered network (300 AC nodes, 43 CH4 nodes)
[ ] If not: Test if it works when dropping mobility sector prior to spatial clustering
[ ] Fix feasibility issues when taking mobility sector into account.

openego / eTraGo