main: add upload support directly to build

This commit adds support to upload the build image directly to
the target cloud. Currently only ami/AWS is supported.

If the cloud specific configuration is given at the commandline
and the image type is a cloud image the cloud upload will happen
automatically (just like with bib). Incomplete upload config is
an error.

cmd/image-builder/build.go

@@ -21,11 +21,6 @@ func buildImage(pbar progress.ProgressBar, res *imagefilter.Result, osbuildManif
 		opts = &buildOptions{}
 	}
 
-	// XXX: support output filename via commandline (c.f.
-	//   https://github.com/osbuild/images/pull/1039)
-	if opts.OutputDir == "" {
-		opts.OutputDir = outputNameFor(res)
-	}
 	if opts.WriteManifest {
 		p := filepath.Join(opts.OutputDir, fmt.Sprintf("%s.osbuild-manifest.json", outputNameFor(res)))
 		if err := os.MkdirAll(filepath.Dir(p), 0755); err != nil {