fix: findRAVENroot, subSystems, keggRxns, YAML without genes

[edkerk]

Main improvements in this PR:

• fix:
  • regenerated the KEGG166 keggRxns.mat, to fix faulty subSystems
  • handling of subSystems in various functions, RAVEN supports both cell arrays and nested cell arrays
  • YAML file I/O for models without genes
  • runINIT retains params as flag for optimizeProb input
• feat:
  • findRAVENroot stores RAVEN root as MATLAB preference during checkInstallation, to avoid problems when running on HPC clusters

Instructions on merging this PR:

• This PR has develop as target branch, and will be resolved with a squash-merge.
• This PR has main as target branch, and will be resolved as descriped here.

[edkerk]

Tests pass locally