activation: Move out code that monitors for ubi services

Move the code that monitors for ubi services into the ubi
subdirectory. Other filesystem layouts can just ignore
the service monitoring by setting the *VolumeCreated
variables to true.

Tested: Verified code update on Witherspoon still worked.

Change-Id: I135e66225d0e8d692d430efd864252b822b069db
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/flash.hpp b/flash.hpp
index 470d99c..5069680 100644
--- a/flash.hpp
+++ b/flash.hpp
@@ -22,6 +22,11 @@
      * @brief Writes the image file(s) to flash
      */
     virtual void flashWrite() = 0;
+
+    /**
+     * @brief Takes action when the state of the activation service file changes
+     */
+    virtual void onStateChanges(sdbusplus::message::message& msg) = 0;
 };
 
 } // namespace updater