n-api: add check for large strings

n-api uses size_t for the size of strings when specifying
string lengths.  V8 only supports a size of int.  Add
a check so that an error will be returned if the user
passes in a string with a size larger than will fit into
an int.

PR-URL: https://github.com/nodejs/node/pull/15611


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>