Add CLI bash completions for user-named resources

[deliahu]

Description

Add CLI bash completion of APIs and environments. Environments is lower priority.

Additional Context

• The operator will need an endpoint to provide the list of APIs. Which env to use? Pull it from the still-being-typed command (e.g. if --env aws is typed already)?
• Env names can be read from the CLI config
• Cobra docs

[vharsh]

/assign

[vikaschenna]

hey @vharsh are you working on it?

[vharsh]

@vikaschenna No, not working on it now.