Utilise `kHighsStatus` returns

[Foggalong]

h.passModel(...) returns a kHighsStatus variable, which indicates whether an issue occurred (see docs). Similarly h.run() returns a kHighsModelStatus (see docs) which indicates whether the model was feasible, unbounded, solved to optimality, etc.

It would be ideal to use these to incorporate readable error handling into the module, rather than relying on a user enabling debug=True and then trawling through pages on pages of logs. This could be leveraged to include slightly more granular output as well.

To do:

• [x] Utilise kHighsStatus return from h.passModel and h.run
• [x] Utilise kHighsModelStatus return from h.getModelStatus()
• [x] Implement controls for granular debug output
• [x] Separate out saving .mps files from debug

[jajhall]

'run()' returns a HighsStatus. The model status that it sets is available as 'getModelStatus()'.

[Foggalong]

Thanks Julian, updated the list accordingly!