Please check if the PR fulfills these requirements
[x] The commit message follows our guidelines
[x] Tests for the changes have been added (for bug fixes / features)
[x] Docs have been added / updated (for bug fixes / features)
Does this PR already have an issue describing the problem?
What kind of change does this PR introduce?
feature
What is the current behavior?
Only the write_matrix_multi_substation_single_line_diagram_svg write a svg of a multi-substation diagram
What is the new behavior (if this is a feature change)?
add the get_matrix_multi_substation_single_line_diagram returning a svg, usable in Jupyter Notebooks
Does this PR introduce a breaking change or deprecate an API?
Please check if the PR fulfills these requirements
Does this PR already have an issue describing the problem?
What kind of change does this PR introduce? feature
What is the current behavior?
Only the write_matrix_multi_substation_single_line_diagram_svg write a svg of a multi-substation diagram
What is the new behavior (if this is a feature change)? add the get_matrix_multi_substation_single_line_diagram returning a svg, usable in Jupyter Notebooks
Does this PR introduce a breaking change or deprecate an API?
Other information: