Read metadata from CZI files instead of .mvl file

[igorpisarev]

CZI parser for Zeiss Z1 acquisitions currently requires an extra .mvl file which is an XML containing acquisition metadata such as positions of the tiles. But CZI files should include this information as well, and it would be better to read the metadata from there directly. This will also make it compatible with other protocols where .mvl files may not be generated.