text: Title: [UX] sky exec CLI does not support dryrun, while sdk does
  Body: ```bash
  sky exec --dryrun test echo
  Usage: sky exec [OPTIONS] [CLUSTER] [ENTRYPOINT]...
  Try 'sky exec -h' for help.
  
  Error: No such option: --dryrun Did you mean --detach-run?
  ```
  
  While [sdk does](https://github.com/skypilot-org/skypilot/blob/2c4849b6f73499740f495f84a29ac4af98d25073/sky/client/sdk.py#L481)
  
  Version:
  ```
  sky -c
  skypilot, commit 2c4849b6f73499740f495f84a29ac4af98d25073
  ```