crypto: generator must be int32 in DiffieHellman()

Validate the generator argument in `crypto.createDiffieHellman(key, g)`.
When it's a number, it should be an int32.

Fixes: https://github.com/nodejs/node/issues/32748

PR-URL: https://github.com/nodejs/node/pull/32739
Fixes: https://github.com/nodejs/node/issues/32738


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Zeyu Yang <himself65@outlook.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>