Validate MP2 Initial Point

[declanmillar]

What is the expected enhancement?

Depends on PRs #590 and #632.

Validate the use of MP2 coefficients as an initial point for VQE using the UCC+HF ansatz that is closer to the ground state, resulting in fewer overall evaluations.

Document this code result in a tutorial to:

1. preserve the result and method for future reference.
2. help users that may want to use MP2 in their own work with an end-to-end working example.