Draft: Move HltEfficiencyChecker docs to DaVinci
Built on top of !3290 (merged) (will stay Draft here until that one is merged)
Goes with DaVinci!1069
Move the HltEfficiencyChecker documentation out of the Moore docs and into DaVinci so that I can use literalinclude
for the examples and not have to keep them updated/aligned by hand - reduces docs maintenance burden.