csharp: Fix passing acessor with ownership
When passing an owned acessor from a converted collection we need a way
to unpin the passed data when the accessor is freed.
This commits adds a thin wrapper around the CArray accessor that unpins
the data when freed.
Depends on D10900
Reviewers: YOhoho, felipealmeida
Reviewed By: YOhoho
Maniphest Tasks: T8486
Differential Revision: https://phab.enlightenment.org/D10901