Is your feature request related to a problem? Please describe.
When running automation using the Okteto CLI it can be flaky and difficult to capture output from okteto namespace list as it only supports plain text output with a * to denote active namespaces, compared to okteto previews list which has a JSON or YAML format output that can be parsed.

Describe the solution you'd like
The same output format options for okteto namespace list

Describe alternatives you've considered
Currently using some grep commands as an alternative.

Additional context
Looking at the code for namespaces and previews there seems to be two ways of constructing cobra commands. Is cmd/preview/list.go the preferred pattern if I was to contribute a similar function for cmd/namespace/list.go?