omit code on action get

**Is your feature request related to a problem? Please describe.**
When doing action get, omit the `code` by default. Instead only fetch the code with `--save[-as]`.

**Describe the solution you'd like**
The code part of an action could be quite large. The API host allows the omission of the `code` property from the response. This would reduce unnecessary fetches from the API host while also keeping the action get result compact.

The API call becomes:
`api/v1/namespaces/_/actions/?code=false`

(note this enhancement would also match `wsk action get` behavior.)

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**
Add any other context or screenshots about the feature request here.