Add useKey support to intl.formatMessage

[Fernando Maia]

• version: 2.3.0
• node version: 10.16.1
• npm (or yarn) version: 6.9.0

Do you want to request a feature or report a bug?:
Feature

What is the current behavior?:
key prop is supported only in <FormattedMessage /> and <FormattedHTMLMessage /> when using useKey option

What is the expected behavior?:
key property could be supported in formatMessage too, e.g.:

props.intl.formatMessage({
  key: 'key'
});

Suggested solution:
Update addIdToFormatMessage visitor to support key property nodePath.

[Paul-Xavier Ceccaldi]

I have the exact same issue!

[akameco]

Done ✅ Install the latest version 🚀