[WIP] Attempt to make optimas generators compatible with generator standard

[RemiLehe]

Overall approach:

optimas generators currently call the ask and tell methods, which, under the hood, can the _ask and _tell methods.

In this PR:

• ask/tell are renamed to ask_trials/tell_trials and keep the same interface (for compatibility with the rest of the framework)
• _ask/_tell are renamed to ask/tell and adopt the new standardized interface.

This allows other packages to use the optimas generators. (In this case, these other packages will call the new, standardized ask/tell directly, without going through ask_trials/tell_trials.)

In order to wrap a standardized generator from another package, one would only need to make a thin wrapper around it that defines ask_trials and tell_trials.

[shuds13]

Looking at this, I think this approach is good. Our current interfacer in Optimas branch #209 used _ask and _tell as we did not want to do the work with Optimas data structures. Now you have moved that outside to ask_trials / tell_trials so this essentially is the same sort of wrapping but instead of ask - > _ask it is ask_trials -> ask.

And the ask can use our gens.

Just need to work out the line to initialize the generator, as you don't have the libE data structures.

We can first try uniform sample, then gpCAM, and then APOSMM via this new interface.

[RemiLehe]

We need to also pass the id here.