[Timeline]: Editing a reply from iOS breaks the "in reply to" rendering (PSG-1168)

[mnaturel]

Type of change

• Feature
• Bugfix
• Technical
• Other :

Content

When getting the last edited content for a reply, we ensure there is a formatted body so that it is still considered as a reply in the timeline.

Motivation and context

According to Matrix specification the formatted body is not mandatory so we should cover missing formatted body cases.
Closes #8150

Screenshots / GIFs

Tests

• From iOS client, send a reply to a message
• From iOS client, edit the reply
• Check in Android client, the message is well rendered in the timeline

Tested devices

• Physical
• Emulator
• OS version(s): Android 11

Checklist

• Changes has been tested on an Android device or Android emulator with API 21
• UI change has been tested on both light and dark themes
• Accessibility has been taken into account. See https://github.com/vector-im/element-android/blob/develop/CONTRIBUTING.md#accessibility
• Pull request is based on the develop branch
• Pull request includes a new file under ./changelog.d. See https://github.com/vector-im/element-android/blob/develop/CONTRIBUTING.md#changelog
• Pull request includes screenshots or videos if containing UI changes
• Pull request includes a sign off
• You've made a self review of your PR
• If you have modified the screen flow, or added new screens to the application, you have updated the test UiAllScreensSanityTest.allScreensTest()

[sonarqubecloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

19.6% Coverage
0.0% Duplication

[ganfra]

LGTM