This doesn't break any extensions NOT using IDataPack, and we do not know of any that are.
* The extension storage utility of this interface has been broken for the last 9 months, with ISourceMod::CreateDataPack being disabled.
* The plugin interop utility of this interface (its stated purpose) has been broken for the last 11+ years, with ISourceMod::GetDataPackHandleType being disabled.
I imagine it only survived the first cleanup 11 years ago because CSS:DM was using it internally, which it has now been migrated away from.
Compiled all the included extensions without changes (API compat), and loaded extensions build pre-change without issue (ABI compat).
Add an ICellArray interface to expose the adt_array CellArray class from
logic to core.
Add methods to ISourceMod to create and delete ICellArray instances in
logic.
