refactor config

[duytiennguyen-okta]

Best practices code, switching config over to query object/method style of behavior. Let the config tell us its state, don't make decisions about state outside of the config.

[monde]

@duytiennguyen-okta can you fill out a description of the PR with the background on the changes?

I'm not sure if I agree with having a bunch more code for getters to do information hiding on the config struct. The config struct is for the application's benefit, we own this code, we aren't exposing it as a public SDK. Outside callers aren't going to be modifying values on the public fields. Even our use of a linter for code quality is forcing listing extra comments for self evident values, for example // OrgDomain --. Also, my understanding of a good time to have getters are to define them on an interface as a contract for the domain logic the interface represents. I'm on the fence on the getters.

That said, I do see the value in having shelf checking setters for input validation. But if you are going to the extra effort to improve input validation why don't you also have unit tests on your setters?

err = cfg.SetAWSSessionDuration(attrs.AWSSessionDuration)
	if err != nil {
		return nil, err
	}
``

[monde]