use DifferentiationInterface in the landau model

[KristofferC]

Ref #1229

[termi-official]

Should we move this now from Gallery to How-To and rename the title here to something like Automatic Differentiable Assembly?

Also, can we add some simple regression test here?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (7a428b0) to head (7b9dd9d).

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #1258   +/-   ##
======================================
  Coverage    0.00%   0.00%           
======================================
  Files          40      40           
  Lines        6572    6572           
======================================
  Misses       6572    6572           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.