WebRowsetBuilder compile fix.

Author: cpwright

web/client-api/src/main/resources/io/deephaven/web/super/io/deephaven/engine/rowset/WebRowSetBuilderSequentialImpl.java

@@ -10,6 +10,11 @@ public void appendRange(long rangeFirstRowKey, long rangeLastRowKey) {
         rangeSet.addRange(new Range(rangeFirstRowKey, rangeLastRowKey));
     }
 
+    @Override
+    public void appendKey(long key) {
+        rangeSet.addRange(new Range(key, key));
+    }
+
     @Override
     public void accept(long first, long last) {
         appendRange(first, last);