Remove all sensitive export functionality from airflowctl

[potiuk]

Body

Make sure all export functionality for connections and variables is removed from airflowctl and replaced with explanation that export can only be available via local CLI.

Make sure import is available.

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.

[amoghrajesh]

@henry3260 could you comment on this issue so we can assign this one to you?

[henry3260]

@amoghrajesh Sure :)

[amoghrajesh]

Assigned.