Optimizers should allow to set the penalty factor for the linear constraint to penalty conversion

[stefan-woerner]

Qiskit allows to add linear equality constraint to the objective as quadratic penalty terms, multiplied by a large constant, the penalty factor.
Currently, not all optimizers allow to manually set this factor upfront.
This needs to be adjusted accordingly.

[dlyongemallo]

I might be interested in looking into this. Is this change intended to be made to the base optimizer class or to specific optimizers only? Can you give more details?

[t-imamichi]

In the previous version, docplex translator can compute the minimum penalty factor automatically. It would be nice to import the logic to the new optimization stack.
https://github.com/Qiskit/qiskit-aqua/blob/bae0ec35dfdbd68a03a0c1db82a3655a7c28d2ea/qiskit/optimization/ising/docplex.py#L237

[a-matsuo]

Created PR #1043 for this issue.