Fixed foreign file system detection

This commit fixed the upload of files located on a file system
provider different from the one where the workflow work directory
is located.

Checking the file system instance is a bad strategy
because there could be multiple file system instances for the
same provider. For example the Google Storage file system
provider creates a new file system instance for each bucket.
Therefore the FilePorter would create a copy of file located
in a bucket X when the pipeline work directory is located in
the bucket Y.

Checking instead the file system provider scheme prevent to
copy files co-located in the same provider.

src/main/groovy/nextflow/file/FilePorter.groovy

@@ -70,7 +70,7 @@ class FilePorter {
         for( Map.Entry<String,Path> entry : filesMap ) {
             def name = entry.getKey()
             def path = entry.getValue()
-            if( path.fileSystem == stagingDir.fileSystem )
+            if( path.scheme == stagingDir.scheme )
                 continue
             // copy the path with a thread pool
             actions << { new NamePathPair(name, stageForeignFile(path)) } as Callable<NamePathPair>

subprojects/nxf-commons/src/main/nextflow/extension/FilesEx.groovy

@@ -1482,12 +1482,16 @@ class FilesEx {
     static String toUriString( Path path ) {
         if(!path)
             return null
-        def scheme = path.getFileSystem().provider().scheme
+        final scheme = getScheme(path)
         if( scheme == 'file' )
             return path.toString()
         if( scheme == 's3')
             return "$scheme:/$path".toString()
         else
             return path.toUri().toString()
     }
+
+    static String getScheme(Path path) {
+        path.getFileSystem().provider().getScheme()
+    }
 }