ENH: deal properly with metadata in the write_texture function of the io module

There is a TODO tag in this function to properly manage file metadata. For this issue to be properly addressed metadata to handle need to be precised

Locate the io module and the write_texture function, then inspect its TODO and surrounding metadata handling. The issue does not specify which metadata must be supported, so clarify the required metadata and expected behavior before implementation. Done means the agreed metadata is handled correctly and covered by appropriate tests.

Written by the indexing model from the issue text.