Migrate ImgLib2 to new SCIFIO API for file I/O

Previously, various ImgLib2 components were using the imglib2-io
library, which is no longer maintained, with all new development having
moved to io.scif:scifio (https://github.com/scifio/scifio).

This change updates all ImgLib2 components to depend on io.scif:scifio
instead. The API is mostly unchanged, although there are a few
differences.
Remove obsolete imglib2-io project

Components needing the ImgOpener and ImgSaver functionality should
depend on io.scif:scifio (https://github.com/scifio/scifio), which
provides up-to-date implementations of these classes and more.