Enable option in ManagedArray that uses std::vector instead of CHAI::ManagedArray

[rrsettgast]

Is your feature request related to a problem? Please describe.
Ben needs this so that he doesn't have conflicting version of chai when coupling ale3d to geosx.

Describe the solution you'd like
#ifdef it and it can be a compile time option.

[corbett5]

We talked about this before, does it need to be a std::vector, or can I just make the ChaiVector allocate it's own memory through new? The problem with simply using a std::vector instead of the ChaiVector is that it actually changes the behavior of the ManagedArray due to the copy constructor and what not.

I guess my point is if the goal is to be able to compile without chai it would be easier to make the ChaiVector just allocate it's own memory than to put a std::vector into ManagedArray.

[rrsettgast]

The problem is that @liu15 can't have to different versions of CHAI. The version used by vista and the one used by GEOSX. So to proceed with his work, he has to use a pre-CHAI commit of GEOSX. This is obviously non-optimal.

It is your call on how to best make it work, but I would think that having ChaiVector hold a shared pointer to a std::vector would be the easiest approach.

[corbett5]

#137