Display ground disconnector in single line diagrams

[So-Fras]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Does this PR already have an issue describing the problem?
Linked to powsybl/powsybl-core#2757 in powsybl-core

What kind of change does this PR introduce?
Bug fix

What is the current behavior?
The ground disconnectors are currently displayed as mere disconnectors. The resulting single-line diagrams aren't readable.

NB: displaying ground disconnectors as disconnectors is not the only problem. A work has to be carried out regarding the dangling internal connection on one of the ground disconnector side.

What is the new behavior (if this is a feature change)?
Ground disconnectors have a specific representation and no dangling internal connections appear on the single-line diagram.

Does this PR introduce a breaking change or deprecate an API?

• The Breaking Change or Deprecated label has been added
• The migration guide has been updated in the github wiki (What changes might users need to make in their application due to this PR?)

[sonarcloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

1 New issue
0 Security Hotspots
96.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud