Feature Request: Flag that optionally sorts the instances as per the list of allowed instance types

[sunnynew]

Summary

Would like have a flag that optionally sorts the instances as per the list of allowed instance types, instead of the price (cheapest) like in the current implementation.

This will also allow us to have diversified instance types in single ASG.

[lenucksi]

This is related to #263.
For this, there would be a need to order the instances in some way, after retrieving the list of allowed instances.
One could randomize the order of the instances (below a certain cost threshold) for every run and then attempt to launch from this. A more deliberate sorting by some criterion would be nice, too.

All in all this basically boils down to having diverse launch candidate list generation strategies. Would need some work to enable configuration of which strategy to use, too.

I'm happy to take PR's on top of #306 and discuss them.

[cristim]

@sunnynew is this issue still of interest to you?