adds Closeable interface to image loaders with a close method

[NicoKiaru]

This PR simply adds a Closeable interface to Image Loaders which already contained a close() method.

This would allow to replace

			if ( imgLoader instanceof N5ImageLoader )
			{
				( ( N5ImageLoader ) imgLoader ).close();
			}
			else if ( imgLoader instanceof N5OMEZarrImageLoader )
			{
				( ( N5OMEZarrImageLoader ) imgLoader ).close();
			}
                       else if ( imgLoader instanceof Hdf5ImageLoader )
			{
				( ( N5OMEZarrImageLoader ) imgLoader ).close();
			}

with

if ( imgLoader instanceof Closeable) {
	( ( Closeable) imgLoader ).close();
}