Unignore user must perform an initial sync

[bmarty]

Type of change

• Feature
• Bugfix
• Technical
• Other :

Content

Displaying a confirmation dialog when a user is unignored, and perform an init sync when it's done:

• from the main setting screen
• from the room member list
• from the slash command action

Motivation and context

Closes #3439

Screenshots / GIFs

From room member list	From settings	From slash command

Tests

• Ignore a user
• Unignore a user -> observe the initial sync

Tested devices

• Physical
• Emulator
• OS version(s):

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()

[github-actions]

Unit Test Results

114 files  ±0  114 suites  ±0   1m 21s ⏱️ -9s
201 tests ±0  201 ✔️ ±0  0 💤 ±0  0 ❌ ±0 
674 runs  ±0  674 ✔️ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit b1cff1a. ± Comparison against base commit 9b7e94e.

♻️ This comment has been updated with latest results.

[bmarty]

I guess this is OK not to create a new string. The translations will be updated one by one, but the use case is not performed a lot.

[ariskotsomitopoulos]

The PR looks fine. We need the Initial Sync in order to fetch already ignored messages? or there is another reason?

[bmarty]

Thanks for your fast review!

The PR looks fine. We need the Initial Sync in order to fetch already ignored messages? or there is another reason?

Yes, the server does not send the message from ignored users to the client. So once the account data is updated, we have to perform a new complete sync.