ENH: basicSpecieThermo: Updated solver references to mixture class

applications/solvers/combustion/PDRFoam/createFields.H

applications/solvers/combustion/XiFoam/createFields.H

applications/solvers/combustion/chemFoam/chemFoam.C

applications/solvers/combustion/chemFoam/createFieldRefs.H

applications/solvers/combustion/fireFoam/createFields.H

applications/solvers/combustion/reactingFoam/createFields.H

...ustion/reactingFoam/rhoReactingBuoyantFoam/createFields.H

...rs/combustion/reactingFoam/rhoReactingFoam/createFields.H

...el/chemistryModel/TDACChemistryModel/TDACChemistryModel.C