text: Title: Add a way for "ploomber task" cli to print task metadata
  Body: Sometimes I want to take a look at the metadata stored from a given task (like the source code, params, last time it ran), but the CLI doesn't offer an easy way to do this, so I'm thinking:
  
  ```sh
  ploomber task {task-name} --metadata
  ```
  
  Should print:
  
  * source code stored in metadata
  * params
  * timestamp
  
  Relevant files:
  
  https://github.com/ploomber/ploomber/blob/master/src/ploomber/cli/task.py
  
  https://github.com/ploomber/ploomber/blob/master/src/ploomber/products/metadata.py
  