Log message when a config file value is overridden by a command line value

The --config option allows users to specify password secrets in a configuration file. These values can be overridden by corresponding options on the command line (e.g. "password: abc" in a config file, but --password="def" on the command line will result in "def").

While documented, the behavior itself is opaque so we should let users directly know what's being overridden. A log message like "WARNING: Overriding value in <config file path> with [--password|--uri|--sslPEMKeyPassword]" would be sufficient.

This should be done after any conversions to pointers since that'll make the checks much easier.