implement function using regex instead of nxf code

src/main/resources/io/viash/platforms/nextflow/functions/_resolveSiblingIfNotAbsolute.nf

@@ -6,14 +6,13 @@
   *
   * @return The path that may have been resovled, as a Path.
   */
-
 def _resolveSiblingIfNotAbsolute(str, parentPath) {
   if (str !instanceof String) {
     return str
   }
-  strAsPath = file(str, hidden: true, relative: true)
-  if (!strAsPath.isAbsolute()) {
-    return parentPath.resolveSibling(str) 
+  if (_stringIsAbsolutePath(str)) {
+    return parentPath.resolveSibling(str)
+  } else {
+    return file(str, hidden: true)
   }
-  return strAsPath
-}
+}

src/main/resources/io/viash/platforms/nextflow/functions/_stringIsAbsolutePath.nf

@@ -0,0 +1,16 @@
+/**
+  * Check whether a path as a string is absolute.
+  *
+  * In the past, we tried using `file(., relative: true).isAbsolute()`,
+  * but the 'relative' option was added in 22.10.0.
+  *
+  * @param path The path to check, as a String.
+  *
+  * @return Whether the path is absolute, as a boolean.
+  */
+def _stringIsAbsolutePath(path) {
+  _resolve_URL_PROTOCOL = ~/^([a-zA-Z][a-zA-Z0-9]*:)?\\/.+/
+
+  assert path instanceof String
+  return (path =~ _resolve_URL_PROTOCOL).size() > 0
+}