Implement an input widget for URIs

[ctrueden]

Such URIs might be a file path (with implicit file:// prefix), so the Browse button is still useful. But when a non-file URI such as https://... or s3://... is given, it should not mangle it into a java.io.File.

A URIWidget interface in SciJava Common is straightforward; the trickier part is here in scijava-ui-swing, how to get all the same features as the current FileWidget, while minimizing copy-pasting of code. I would like to make an abstract SwingFileEtcWidget or some such, which still takes a generic parameter for data type, but has the common logic for the Browse button for picking files...

[ctrueden]

See also #84, which should be merged in a coordinated fashion as part of this refactoring. CC @tischi

[imagesc-bot]

This issue has been mentioned on Image.sc Forum. There might be relevant details there:

https://forum.image.sc/t/scijava-gui-that-works-for-both-local-and-remote-storage/98313/5