Replace count prop from <Trans> in translation string automatically

[manuelbieh]

Is your feature request related to a problem? Please describe.
As already discussed on Twitter:
https://twitter.com/ManuelBieh/status/1117491118223106048

The current usage of the Trans component:

<Trans i18nKey="messageCount" count={3}>
  You have <strong>{{count: 3}}</strong> new messages.
</Trans>

with translation keys being:

messageCount: "Du hast <1>{{count}}</1> neue Nachricht",
messageCount_plural: "Du hast <1>{{count}}</1> neue Nachrichten",

feels unnecessarily complicated and also redundant if you're not using a variable for count. The value for count can possibly be replaced automatically based on the value that is passed to the count prop in the Trans component, so that this would be possible:

<Trans i18nKey="messageCount" count={3}>
  You have <strong>?</strong> new messages.
</Trans>

Describe the solution you'd like
I'd love to see this working:
https://codesandbox.io/s/oqj2o017w9

[jamuhl]

works in [email protected]

[manuelbieh]

Schneller als die Feuerwehr 🚒 👨‍🚒 . Nice! Thank you!