Added feature: hide specified keys

[mps-pso]

This features creates the ability for users to hide env variables which are particularly sensitive or simply not needed.

This will allow a user to pass the an array of env variables to the ->hideKeys() method to have them filtered out.

[GeoSot]

Thanks a lot @mps-pso. Please check if you agree with my committed suggestions, and we can proceed

[mps-pso]

Apologies, I forgot to add the linting

[mps-pso]

Swapped from array to strings