feat(MCOL-6082): Multiple readers of dbroots using OamCache logic

This patch introduces centralized logic of selecting what dbroot is
accessible in PrimProc on what node. The logic is in OamCache for time
being and can be moved later.

dmlproc/batchinsertprocessor.h

@@ -68,6 +68,7 @@ class BatchInsertProc
   void setHwm();
   void receiveAllMsg();
   void receiveOutstandingMsg();
+  uint32_t selectNextPM();
 
  private:
   SP_PKG fInsertPkgQueue;