Implement best checkpointer#75

Draft

nifarn wants to merge 3 commits intomicrosoft:mainfrom

nifarn:nifarn/best-checkpointer

Commits on Dec 3, 2021

initial implementation of best checkpointer
nifarn
committed

Commits on Dec 4, 2021

made criteria logic more universal
nifarn
committed

Commits on Dec 15, 2021

changes to best checkpointer logic from suggestions
nifarn
committed