feature/api5: Add a deserializer for old legacy IDs

[alvin0319]

Is your feature request related to a problem? Please describe. In PM5, all legacy IDs have been removed from the core and are no longer be used. This is problematic when we upgrade from PM4, which PocketMine cannot understand custom item IDs, which might lead to data lost.

Describe the solution you'd like Add a hack to convert legacy ID to newer format. This probably won't hard but need more investigation.

Describe alternatives you've considered Described above.

Additional context N/A