Keep GraphQL subscriptions active only on a single tab in Web (#1047)

[SleepySquash]

Part of #1047

Synopsis

Each new instance of application opens the same subscriptions over and over again, even if those instances all share the same database, which just spams the backend and it isn't good.

Solution

Since drift supports real-time local changes subscription propagating, this renders having to open multiple GraphQL subscriptions useless: one tab may connect to the updates and the other ones can just get those updates via drift subscriptions.

The current idea is to use WebUtils.protect, so that tabs don't invoke subscriptions at the same time at all. After some testing the idea seems to be working. The bugs left to fix:

• ChatItems don't get real-time updates from drift, user must re-enter the chat for new messages from drift to appear. This is because SQL query executes only after re-entering the chat. Should refactor that to be a watch. Moved to Refactor RxChat.mesages pagination to watch() changes from drift #1060

Checklist

• Created PR:
  • In draft mode
  • Name contains issue reference
  • Has type and k:: labels applied
• Before review:
  • Documentation is updated (if required)
  • Tests are updated (if required)
  • Changes conform code style
  • CHANGELOG entry is added (if required)
  • FCM (final commit message) is posted or updated
  • Draft mode is removed
• Review is completed and changes are approved
  • FCM (final commit message) is approved
• Before merge:
  • Milestone is set
  • PR's name and description are correct and up-to-date
  • All temporary labels are removed

[SleepySquash]

UPD. Moved to #1060

The bugs that should be addressed:

1. Favourite Chat position changing isn't synced via drift for some reason.
2. Draft: is blinking rapidly when sending new messages.

[SleepySquash]

FCM

Guard GraphQL subscriptions with `WebUtils.protect()` to ensure no simultaneous execution (#1055, #1047)

Additionally:
- fix `ApplicationSettings` being used with default values by awaiting `SettingsRepository.init()`