Allow meshed control transformers

[nitbharambe]

Changes proposed in this PR include:

The updated implementation of automatic transformer tap changer was too restrictive on allowed cases for tap control. Meshed control of transformers was not allowed. With this PR, we shall now put the rank of transformer at the end of the mesh to a last_rank. Controlling the slack bus is still prevented by this way.

[mgovers]

Do not merge label temporarily added so that we can merge #908

EDIT: Removed after successful merge of #908 and #937

[petersalemink95]

Added do-not-merge label, because we have not made a decision on the right implementation yet

[petersalemink95]

If we are going to merge this branch, we should clearly document which cases we do and which we do not support in automatic tap calculations

[Jerry-Jinfeng-Guo]

Added do-not-merge label, because we have not made a decision on the right implementation yet

Please only remove the label once we get the go signal from stakeholders.

[sonarqubecloud[bot]]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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