Make AWT and Swing projects external

See:
* https://github.com/imagej/imagej-ui-awt
* https://github.com/imagej/imagej-ui-swing
* https://github.com/scijava/scijava-ui-awt
* https://github.com/scijava/scijava-ui-swing
WIP: Make Updater project external

See:
https://github.com/imagej/imagej-updater