This change is to improve code coverage (and to simplify #5720 and #5725); there is otherwise no change in functionality. The change adds basic tests for `STInteger` and `STParsedJSON`, so it becomes easier to test smaller changes to the types, as well as removes `STParsedJSONArray`, since it is not used anywhere (including in Clio).
The codebase is filled with includes that are unused, and which thus can be removed. At the same time, the files often do not include all headers that contain the definitions used in those files. This change uses clang-format and clang-tidy to clean up the includes, with minor manual intervention to ensure the code compiles on all platforms.
