fix: Fix some of the French i18n translations

[tmoran-stenoa]

🎯 Goal

Fix a few inaccurate or missing French translations.

🛠 Implementation details

I am a native French speaker from Canada. I was reviewing the French translations and found that a few of them were inaccurate, missing, or had some grammatical or semantic errors, so I volunteered to make a few fixes.

Note: I have not tested the changes. Feel free to accept/reject/modify any of the changes I made.

🎨 UI Changes

iOS

Before	After

Android

Before	After

🧪 Testing

Change your app to French and check that the translations render properly and that they make sense.

☑️ Checklist

• I have signed the Stream CLA (required)
• PR targets the develop branch
• Documentation is updated
• New code is tested in main example apps, including all possible scenarios
  • SampleApp iOS and Android
  • Expo iOS and Android

[isekovanic]

Hi @tmoran-stenoa ,

Thanks for your contribution ! I'll have a look at this soon.