WIP: Bugfix with knob changing when calling jacobian

[babreufig]

Description

When calculating the jacobian, the state (knob values) is restored after returning the jacobian. Previously it would change the optimize object to store the knob values given for jacobian with the last step.

Checklist

Mandatory:

• I have added tests to cover my changes
• All the tests (in xdeps) are passing, including my new ones
• I described my changes in this PR description

Optional:

• The code I wrote follows good style practices (see PEP 8 and PEP 20).
• I have updated the docs in relation to my changes, if applicable
• I have tested also GPU contexts