add snakemake rule for rsync dry-run (#1402)

Snakefile

@@ -138,3 +138,15 @@ rule sync:
         rsync -uvarh --no-g {params.cluster}/results . || echo "No results directory, skipping rsync"
         rsync -uvarh --no-g {params.cluster}/logs . || echo "No logs directory, skipping rsync"
         """
+
+
+rule sync_dry:
+    params:
+        cluster=f"{config['remote']['ssh']}:{config['remote']['path']}",
+    shell:
+        """
+        rsync -uvarh --ignore-missing-args --files-from=.sync-send . {params.cluster} -n
+        rsync -uvarh --no-g {params.cluster}/resources . -n || echo "No resources directory, skipping rsync"
+        rsync -uvarh --no-g {params.cluster}/results . -n || echo "No results directory, skipping rsync"
+        rsync -uvarh --no-g {params.cluster}/logs . -n || echo "No logs directory, skipping rsync"
+        """