Add an closed loop network model for BHE array benchmark and update the BHE array tutorial accordingly
This PR is the complement for the Merge Request(!3070 (merged)). Based on the basic configuration in the BHE array benchmark, an closed loop TESPy network was constructed and simulated in this case besides the original one-way network model. The two network models share the project and mesh files in this benchmark. The results description using with the closed loop network model was added in the benchmark documentation. Besides, the user-guide of BHE array tutorial was updated accordingly.
Detailed descriptions in this PR are listed as followed:
- An closed loop TESPy network was constructed for BHE array benchmark. Full time results and related descriptions were added in the benchmark documentation.
- the user-guide of BHE array tutorial was updated according to the newly constructed closed loop network model.