Lagoon post-rollout tasks with complex quotations are handled badly

[tobybellwood]

When running a post rollout task
eg

  post-rollout:
    - run:
        name: drush updb
        # This will only run if the database exists.
        command: |
          if [[ $(drush status --field=Database) == "Connected" ]]; then drush -y updb; fi
        service: cli
        shell: bash

The runner attempts to quote everything it doesn't recognise, and this results in nasty shell errors

cli-drupal:/app$ if [[ $(drush status --field=Database) == "Connected" ]]; then drush -y updb; fi
cli-drupal:/app$ drush lagoon:post-rollout-tasks
> sh: syntax error: unexpected end of file (expecting "then")

In SiteProcess.php line 214:
                                                                                                         
  The command "if '[[' '$(drush' status '--field=Database)' == Connected ']];' then drush -y 'updb;' fi  
  " failed.                                                                                              
                                                                                                         
  Exit Code: 2(Misuse of shell builtins)                                                                 
                                                                                                         
  Working directory:                                                                                     
                                                                                                         
  Output:                                                                                                
  ================                                                                                       
                                                                                                         
                                                                                                         
  Error Output:                                                                                          
  ================                                                                                       
  sh: syntax error: unexpected end of file (expecting "then")