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/activation.hpp b/activation.hpp
index 55377b1..9315fc8 100644
--- a/activation.hpp
+++ b/activation.hpp
@@ -249,6 +249,9 @@
     /** @brief Overloaded write flash function */
     void flashWrite() override;
 
+    /** @brief Overloaded function that acts on service file state changes */
+    void onStateChanges(sdbusplus::message::message&) override;
+
     /** @brief Check if systemd state change is relevant to this object
      *
      * Instance specific interface to handle the detected systemd state