Report alive continuation Objects in verbosegc

[LinHu2016]

Report total alive and started continuation Objects in mem-info of verbosegc log.

• piggyback iterateAllContinuationObjects(), which is designed to help improving the performance of jit code cache reclamation, to collect total and started numbers of continuation at the end of GC.
• report tag continuationObjects in of verbase gc if total alive continuation Objects isn't 0.

limitation of this changes: in case iterateAllContinuationObjects() helper is not run, no counts would be collected and reported, such as case1: scavenger backout case case2: disable jitcodecacheReclaim feature case3: there is no need jitcodecachereclamation for the cycle case4: runtime GC (there is no iterateAllContinuationObjects() helper in runtime GC).

depends on: https://github.com/eclipse/omr/pull/7386

Signed-off-by: hulin [email protected]