Reduce the number of package level variables

Expected Behaviour

It would be nice/better if the CLI flag values were scoped to the methods being run instead of the package, e.g. we shouldn't expose the secretName variable to the deploy command.

Current Behaviour

Many (or all) of the CLI commands have flag values that are parsed by supplying a pointer to a package level variable, e.g.

cmd.Flags().StringVar(&name, "name", "", "Secret name")

Possible Solution

Flag values can be parsed and retrieved via the getter methods, for example

secretValue, err := cmd.Flags().GetString("from-literal")
if err != nil {
     return err
}

Context

This idea was discussed during teh review of #580

Start by locating the CLI commands that bind flags with package-level variables, such as the StringVar example for the name flag. Review the related discussion in issue #580 and compare the commands' flag definitions and handlers. Done means flag values are scoped to the commands or methods that use them rather than exposed through package-level variables.