New Issue: [Library Stabilization] 'bigint.mod' int implementation

17713, "lydia-duncan", "[Library Stabilization] 'bigint.mod' int implementation", "2021-05-12T22:34:40Z"

The documentation for the bigint version in GMP says that the sign of the bigint is ignored, but for our int implementation we cast any negative values to a uint to call the version that returns a remainder as well. In other cases we convert ints to bigints and call the bigint version, should we do the same for ints here instead? That might involve splitting into separate functions since that version wouldn't return a remainder. Or should the uint version do the same thing instead of calling mpz_mod_ui (which is the uint specific implementation)?