Allow CLI configuration to be saved to a file

[amisevsk]

Describe the problem you're trying to solve
As the CLI becomes more complex and gains more options, it would be convenient to be able to set some/all of them persistently in a configuration file. This will become increasingly useful as e.g. more networking options are added.

Describe the solution you'd like
Kit should provide a kit config command to allow configuring common options available as flags and saving that configuration between invocations. This configuration should be saved to some file (maybe in the $KITOPS_HOME directory, or separate Kit config directory) and these settings should be used instead of default values for corresponding flags.

Describe alternatives you've considered
Mainly, deferring this work until there are enough flags we're specifying on every invocation where the moderately increased complexity of supporting a config file makes sense.

Additional context
Related: #365 -- we want to be able to persistently disable update notifications, for example.

[SkySingh04]

This sounds like a fun and interesting issue to work on! This will require a little bit of work but lets do this!

I had a question : are we supposed to store config for all flags for all commands or for just the root command?