Note that DynamicModel::determineBlockDerivativesType(), it’s legitimate to
replace max_{lead,lag} by max_endo_{lead,lag}, because for exogenous
lag=lead=0, and we no longer compute derivatives w.r.t. to endogenous that do
not belong to the block (so-called “other” endogenous).

Bytecode w/ block decomposition: no longer output derivatives w.r.t. exogenous and endogenous outside the block

Also improve the naming of the enum class used for identifying the type of
external function call.