cloudapi: add option to upload S3 artifacts publicly

A small test is added to cover this new option. Also, a check for AWS region
in the URL was removed. The public URL doesn't actually contain it and it's
imho useless - S3 buckets are always tied to a certain region.

The elaborate grep command parsing a path from a URI was switched to being
a small python script. The python script can actually handle an URI without
a query (which was always present in the pre-signed URI, but it's not in the
ordinary one)

Signed-off-by: Ondřej Budai <ondrej@budai.cz>

internal/cloudapi/v2/handler.go

@@ -375,10 +375,16 @@ func (h *apiHandlers) PostCompose(ctx echo.Context) error {
 					return HTTPError(ErrorJSONUnMarshallingError)
 				}
 
+				public := false
+				if awsS3UploadOptions.Public != nil && *awsS3UploadOptions.Public {
+					public = true
+				}
+
 				key := fmt.Sprintf("composer-api-%s", uuid.New().String())
 				t := target.NewAWSS3Target(&target.AWSS3TargetOptions{
 					Region: awsS3UploadOptions.Region,
 					Key:    key,
+					Public: public,
 				})
 				t.ImageName = key
 				t.OsbuildArtifact.ExportFilename = imageType.Filename()