[GeneralDichotomy] handle no solution case

[smbct]

In reply to #203:

I replaced the initial scalarization by w=(1, .., 1). The missing solution case can be detected at the beginning by solving a simple sum of the objectives:

• if one of the objective is unbounded, any sum with non zero coefficients should be also unbounded
• if the problem is infeasible, any linear scalarization should be infeasible as well

Then, if any sub-problem is infeasible, this must be due to numerical issues, hence returning MOI.NUMERICAL_ERROR in the main loop.

(PS sorry for the duplicate PR)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.57%. Comparing base (b71397a) to head (d7d30c7).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #207      +/-   ##
==========================================
- Coverage   99.64%   99.57%   -0.08%     
==========================================
  Files          15       15              
  Lines        1421     1420       -1     
==========================================
- Hits         1416     1414       -2     
- Misses          5        6       +1     

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