Add evaluation of additional operators

[Cryoris]

Summary

Add the possibility to pass a dictionary of auxiliary operators to compute_groundstate and transform.

Details and comments

• changed the data structure of aux operators from a list to a dictionary: {str: FermionicOperator/BosonicOperator}
• the type hint in cases where fermionic and bosonic is supported is Any but could possible be Union[FermionicOperator, BosonicOperator] once we have the bosonic operator
• fixed a bug in adapt VQE where the values of the aux operators were not stored

Open questions

1. The MinimumEigensolver interface also supports aux operators but there they are a list. Since this is a mathematically abstract solver w/o any interpretation it might make sense to keep them as list there. This is what's done now.
2. Are we breaking backwards compatibility somewhere by changing list->dict?

[mrossinek]

I left some minor comments.
I can't think of any place where we would need to add a DeprecationWarning for the type change from list to dict. But maybe the others can think of something.

[pbark]

I think that now it looks ok. Should I merge it or are there any other comments?

[mrossinek]

There are some leftovers from the dict-style aux_ops.

[mrossinek]

lgtm 👍

[woodsp-ibm]

I think the aux op values, like the eigen values - were always complex numbers so far