crit-service: refactor unit state checking

Break this out into generic function so it can be utilized to also look
at the new new quiesce target in a future commit

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: I1277606d10c1d8e0eafc120ad1fd6cdf80013abd
diff --git a/bmc_state_manager.hpp b/bmc_state_manager.hpp
index 4ea9784..ee97070 100644
--- a/bmc_state_manager.hpp
+++ b/bmc_state_manager.hpp
@@ -70,6 +70,10 @@
 
   private:
     /**
+     * @brief Retrieve input systemd unit state
+     **/
+    std::string getUnitState(const std::string& unitToCheck);
+    /**
      * @brief discover the state of the bmc
      **/
     void discoverInitialState();