Smartling formatter missing string_format:icu

[hjylewis]

Which package?

cli

Describe the bug

According to the smartling docs, the smartling configuration should also include the property string_format: "icu" to indicate that the messages are ICU MessageFormat.

So the SmartlingDirectives should be

{
  smartling: {
    translate_paths: [
      {
        path: '*/message',
        key: '{*}/message',
        instruction: '*/description',
      },
    ],
    variants_enabled: true,
    string_format: 'icu'
  },
}

I'll try to open a PR for this.