1116 add dual variables into the output list in the template

[nnhjy]

1. Add in the current template the dual values as output
2. Add a dummy parameter to classify the output values

Fixes #1116

Checklist before merging

• Documentation is up-to-date
• Unit tests have been added/updated accordingly
• Code has been formatted according to SpineOpt's style
• Unit tests pass

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.38%. Comparing base (bb5c565) to head (1659218).
Report is 13 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1121      +/-   ##
==========================================
+ Coverage   87.33%   87.38%   +0.04%     
==========================================
  Files         143      143              
  Lines        4137     4137              
==========================================
+ Hits         3613     3615       +2     
+ Misses        524      522       -2     

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[nhniina]

Indentations are sometimes off and we could still discuss with other SpineOpt developers what is the best way to group the outputs. Let's also ensure that an issue is created about the problem with several reports linking to one output, so that the FIXME lines don't get lost. Otherwise I think this looks ready for merging.