Allow input of counterfactual (intervention) probabilities for TRT and MONITOR

[osofr]

Current set-up only permits the input of probabilities/indicators of observation following an intervention-specific treatment and/or monitoring rule (arguments gstar.TRT and gstar.MONITOR).

In some cases it might be more intuitive to have as input the counterfactual values of treatment and monitoring based on some intervention rule (the current functionality of ltmle and tmlenet). For dynamic rules, these would be evaluated for each observation and could also be specified as probabilities of TRT[t]=1 and MONITOR[t]=1, under some intervention rule. In this case, the rule followers/non-followers (gstar.TRT & gstar.N) would be evaluated automatically by comparing the observed TRT/MONITOR to their corresponding counterfactual values/probabilities.