Clarify HiPO option feedback when the solver is unavailable

[NightBaRron1412]

Summary

• hide the HiPO entry from the command-line solver help when the build lacks HiPO support
• emit dedicated error messages for the LP, MIP LP, and MIP IPM solver options when HiPO is requested but not compiled in

[jajhall]

I did this originally, but felt that it was unnecessary. It's no problem to reinstate it if users find it confusing

[NightBaRron1412]

Yeah, that makes sense! I actually got confused myself and spent a while checking if I’d misconfigured the build ... having the CLI indicate when HiPO isn’t compiled in would really help avoid that. Thanks for being open to bringing it back!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.06%. Comparing base (869cbd4) to head (8d49f4e).
⚠️ Report is 4 commits behind head on latest.

Additional details and impacted files

@@           Coverage Diff           @@
##           latest    #2616   +/-   ##
=======================================
  Coverage   81.06%   81.06%           
=======================================
  Files         347      347           
  Lines       85219    85228    +9     
=======================================
+ Hits        69083    69092    +9     
  Misses      16136    16136           

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[galabovaa]

LGTM, thank you!