Callbacks for QP active set method

[jajhall]

Added two callbacks to the QP active set method

• At the request of @cvanaret, after the first feasible point is found (by simplex) the primal solution is made available.
• A standard user interrupt

Also enhanced Highs::checkOracle() slightly and added documentation to advanced.md

[codecov]

Codecov Report

❌ Patch coverage is 92.56757% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.79%. Comparing base (b196d7a) to head (abe932d).
⚠️ Report is 3 commits behind head on latest.

Files with missing lines	Patch %	Lines
highs/model/HighsHessian.cpp	83.33%	6 Missing ⚠️
highs/interfaces/highs_c_api.cpp	50.00%	2 Missing ⚠️
highs/qpsolver/a_quass.cpp	86.66%	2 Missing ⚠️
highs/lp_data/Highs.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #3214      +/-   ##
==========================================
+ Coverage   72.77%   72.79%   +0.01%     
==========================================
  Files         444      444              
  Lines      107469   107541      +72     
  Branches    17290    17309      +19     
==========================================
+ Hits        78213    78281      +68     
- Misses      28979    28983       +4     
  Partials      277      277              

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