[Building Utility] One bugfix, one user-facing change, and general cleanup and documentation

This contains one bugfix, 3e289e2091a2e498ee7f4afe1730f665fda48227. It does not rely on any changes in this pull request, but because I caught it after all this, I don't know how to separate it. Let me know if it is necessary.

The only other notable change is 3f43e7c, a change in syntax, which I feel puts the utility more in line with how the project chooses to write json.

Other than that, this is just code readability and pylint satisfaction.

Here a discussion of future work on Building Utility: https://github.com/CleverRaven/Cataclysm-DDA/issues/8693