Use relative path as execution name (when possible)

tooling-core/src/main/java/org/opentest4j/reporting/tooling/core/htmlreport/DefaultHtmlReportWriter.java

@@ -113,13 +113,21 @@ private List<Execution> extractData(List<Path> xmlFiles, Path htmlFile) throws E
 
 		for (Path xmlFile : xmlFiles) {
 			var rootElement = parseDom(xmlFile);
-			var name = String.format(xmlFile.getFileName().toString());
+			var name = String.format(tryRelativize(htmlFile, xmlFile).toString());
 			executions.add(
 				extractData(idGenerator, rootElement, name, element -> new DefaultContext(element, xmlFile, htmlFile)));
 		}
 		return executions;
 	}
 
+	private static Path tryRelativize(Path htmlFile, Path xmlFile) {
+		try {
+			return htmlFile.getParent().relativize(xmlFile);
+		} catch (IllegalArgumentException e) {
+			return xmlFile;
+		}
+	}
+
 	private static void appendScriptTag(List<Execution> executions, String indent, BufferedWriter out)
 			throws IOException {
 		out.append(indent).append("<script>");