fix: handle `I` as mass matrix for `CheckInit`#880

AayushSabharwal merged 2 commits intoSciML:masterSciML/SciMLBase.jl:masterfrom

AayushSabharwal:as/checkinit-I-mmAayushSabharwal/SciMLBase.jl:as/checkinit-I-mmCopy head branch name to clipboard