CLI argument merging

[dgasmith]

Describe the bug The intention of the CLI with a config file was to allow overrides via the CLI if a configuration file is present. Currently we simply check if the provided value is the default value or not to see if we override. This typically works, but fails when the config file moves to a non-default and then the CLI override uses the default value.

To Reproduce qcfractal-server --start-periodics=True in the CLI and start_periodics: False in a config file. The result will not start the periodics.

Expected behavior CLI passed args should always override the config file.

[dgasmith]

This does not appear to be possible with standard argparse unfortunately. I would rather not have another dependency here either.