Fix prototype pollution in `safeSet` / evaluate other weaknesses

[typhonrt]

safeSet doesn't evaluate protected accessor keys and allows prototype pollution. A bug / issue, but not severe.

See fuzz / example from long abandoned version of this package.
typhonjs-node-utils/typhonjs-object-util#1

Pinging issue reporter @cstimkong for credit.

[cstimkong]

I have created a PR:

#2 (comment)