struct implementing interface is boxed when passed to method that accepts interface (not generic method).
Removes IDexLevel (no other inheritors but EvoCriteria) and uses the primitive the data is stored (array, not IReadOnlyList) for slightly better perf.
Existing `get`/`set` logic is flawed in that it doesn't work on Big Endian operating systems, and it allocates heap objects when it doesn't need to.
`System.Buffers.Binary.BinaryPrimitives` in the `System.Memory` NuGet package provides both Little Endian and Big Endian methods to read and write data; all the `get`/`set` operations have been reworked to use this new API. This removes the need for PKHeX's manual `BigEndian` class, as all functions are already covered by the BinaryPrimitives API.
The `StringConverter` has now been rewritten to accept a Span to read from & write to, no longer requiring a temporary StringBuilder.
Other Fixes included:
- The Super Training UI for Gen6 has been reworked according to the latest block structure additions.
- Cloning a Stadium2 Save File now works correctly (opening from the Folder browser list).
- Checksum & Sanity properties removed from parent PKM class, and is now implemented via interface.
Big thanks to @SciresM @sora10pls @Lusamine @architdate @ReignOfComputer for testing and contributing code / test cases. Can't add co-authors from the PR menu :(
Builds will fail because azure pipelines not yet updated with net6.
