[FEATURE] Provide a generic_branch

[petersalemink95]

Following the discussion in #642 it was concluded that the implementation of a generic branch could be an addition to Power Grid Model.

We can make a new component generic_branch, which models branches as a Pi model; i.e. the user can specify:

• k: transformer ratio (float)
• theta0 / theta1 / theta2: angle shift
• r0_series / r1_series / r2_series
• x0_series / x1_series / x2_series
• g0_shunt / g1_shunt / g2_shunt
• b0_shunt / b1_shunt / b2_shunt

Note: except for k, all attributes are given for zero, positive and negative sequence.

##steps to follow In order to add a new component to Power Grid Model the following steps need to be taken:

• [ ] Check if the available input/update/output data suffices (check power-grid-model/power_grid_model_c/power_grid_model/include/power_grid_model/auxiliary/ input.hpp / update.hpp / output.hpp or in the documentation directly)
• [ ] If not, add the new data format to code_generation/data/attribute_classes/ input.json / update.json / output.json + run code_generation/code_gen.py
• [ ] Create a new component in a new power-grid-model/power_grid_model_c/power_grid_model/include/power_grid_model/component/[component].hpp file that at least inherits from Base, but in this case GenericBranch should inherit from Branch
• [ ] If necessary: add new enums or exceptions
• [ ] Create the necessary unit tests in power-grid-model/tests/cpp_unit_tests/test_[component].cpp
• [ ] Add the test_[component].cpp to power-grid-model/tests/cpp_unit_tests/CMakeLists.txt
• [ ] Add component to power_grid_model_c/power_grid_model/include/power_grid_model/all_components.hpp
• [ ] Not necessary for this component (If necessary update main_core/topology.hpp / input.hpp / output.hpp / update.hpp)
• [ ] Add component to code_generation/data/dataset_class_maps/dataset_definitions.json + re-run code_generation/code_gen.py
• [ ] Add validation test cases to tests/data
• [ ] Update input/update data validator for the new component: src/power_grid_model/validation/validation.py + add corresponding tests

Note: the order is recommended, but not necessary