Use MIASReader.parseMasks (Fix #10170)

Make use of the newly added parseMasks method which doesn't
require closing and re-opening the reader. This commit needs:

openmicroscopy/bioformats@20308cee521787e9ecab341953f84c7e0d08a9b7
Merge pull request #726 from joshmoore/10170-fs-mias

Use MIASReader.parseMasks (Fix #10170)