Alternative way to handle patch string when it's too big to be stored as literal

[dlamoris]

In model load, there's insert/delete graph that can be used: can store the ins/del graph as commit metadata and let BranchWrite detect it/use it, or just always keep them and use this as the patch string instead (these graphs are currently not being deleted so they're just hanging around anyways - also add them as commit metadata so they can potentially be queried):

delete {
    graph ?__mms_model {
        ?s ?p ?o .
    }
} where {
    graph <delGraphIri> {
        ?s ?p ?o .
    }
};
insert {
    graph ?__mms_model {
        ?s ?p ?o .
    }
} where {
    graph <insGraphIri> {
        ?s ?p ?o .
    }
} 

Model commit (sparql update) also need an alternative