Make FilterCriteria.Operator.getSymbol public (#5106)

Signed-off-by: Cody Cutrer <cody@cutrer.us>

bundles/org.openhab.core.persistence/src/main/java/org/openhab/core/persistence/FilterCriteria.java

@@ -56,7 +56,7 @@ public class FilterCriteria {
             this.symbol = symbol;
         }
 
-        String getSymbol() {
+        public String getSymbol() {
             return symbol;
         }
     }