Make LegacyTypeHandling possible

[Johannes Rabauer]

Is your feature request related to a problem? Please describe.
Changing classes or class-structures is painful. If we could handle this in Update-Scripts, this would be a real win.
https://docs.microstream.one/manual/storage/legacy-type-mapping/index.html

Describe the solution you'd like
Automatically adding the LegacyTypeMappings to the init of MicroStream would be a real comfort-functionality.

[Alex B]

@JohannesRabauer

Can you please recheck if the issues here (in the repo) are still valid when you have a bit of spare time?
Thank you in advance.