Refactor: Move determinId to ubi

The function determinId is used only in ubi case, move it to ubi.

Tested: On the last commit of the patch series, run code update and
        factory reset on Witherspoon and all work fine.

Change-Id: I8974d25bf904a5202b913fc185790c5ecf8eca90
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/ubi/item_updater_ubi.hpp b/ubi/item_updater_ubi.hpp
index af330a8..dfc8e53 100644
--- a/ubi/item_updater_ubi.hpp
+++ b/ubi/item_updater_ubi.hpp
@@ -41,6 +41,14 @@
 
     bool isVersionFunctional(const std::string& versionId) override;
 
+    /** @brief Determine the software version id
+     *         from the symlink target (e.g. /media/ro-2a1022fe).
+     *
+     * @param[in] symlinkPath - The path of the symlink.
+     * @param[out] id - The version id as a string.
+     */
+    static std::string determineId(const std::string& symlinkPath);
+
   private:
     /** @brief Callback function for Software.Version match.
      *  @details Creates an Activation D-Bus object.