Add a simply function to plot the dependency tree

[dachengx]

Before you submit this PR: make sure to put all operations-related information in a wiki-note, a PR should be about code and is publicly accessible

What does the code in this PR do / what does it improve?

The function is different from the one in docs/source/build_datastructure_doc.py:build_datastructure_doc. The new function is a much more simplified version.

Can you briefly describe how it works?

Can you give a minimal working example (or illustrate with a figure)?

Please include the following if applicable:

• [ ] Update the docstring(s)
• [ ] Update the documentation
• [ ] Tests to check the (new) code is working as desired.
• [ ] Does it solve one of the open issues on github?

Notes on testing

• Until the automated tests pass, please mark the PR as a draft.
• On the XENONnT fork we test with database access, on private forks there is no database access for security considerations.

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[coveralls]

coverage: 91.28% (-0.07%) from 91.349% when pulling e7e8d0ec7ef4b95f24a7c6231ae37b4539414b0a on dependency_tree into e7d95878b091ebe0a6d80732b256ba677c7a6ba1 on master.