Add env vars for ZARF_LOG_LEVEL and ZARF_LOG_FORMAT

[mkcp]

Is your feature request related to a problem? Please describe.

We don't support env vars for log level and format but these are nice to have for users.

Describe the behavior you'd like

When a user supplies an either the ZARF_LOG_LEVEL ZARF_LOG_FORMAT env var, these should percolate through the CLI layer and into logger setup. In the event that a flag is also supplied, the flag value takes precedence.

[mkcp]

Great news, this is already done with Viper's CLI setup. Neat! I went ahead and tested each combination of config that we added and we're feature complete here. Go team!