Fix local echos not being shown when re-opening rooms

[SpiritCroc]

Signed-off-by: Tobias Büttner dev@spiritcroc.de

Type of change

• Feature
• Bugfix
• Technical
• Other :

Content

Make sure we have frozen results for SendingEventsDataSource right when starting it

Motivation and context

When you open a room which already has local echos, these wouldn't show until you create a new one.

Tests

1. send message while offline
2. close room
3. re-open room
   => Own messages are not showing, until we sync them back after they reached the server, or we send another new message.

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()

[ouchadam]

the change looks reasonable to me 💯 have looped in @ganfra as a reviewer

[ouchadam]

the change looks reasonable to me 💯 have looped in @ganfra as a reviewer

[ganfra]

LGTM, thanks for the fix