Exclude duplicate calls from workspace preview

Signed-off-by: Ben Sherman <bentshermann@gmail.com>

Author: bentsherman

src/main/java/nextflow/lsp/services/script/WorkspacePreviewProvider.java

@@ -67,6 +67,7 @@ private List<? extends Object> children(WorkflowNode node) {
         return new OutgoingCallsVisitor().apply(node).stream()
             .map(call -> TypeChecker.inferMethodTarget(call))
             .filter(mn -> mn instanceof ProcessNode || mn instanceof WorkflowNode)
+            .distinct()
             .map(mn -> Map.of(
                 "name", mn.getName(),
                 "path", ast.getURI(mn).getPath()