[web] Ensure that restore operations are not UI-blocking and still running in suspended tabs

[JammingBen]

Description

User Stories

• As a user I want all restore operations to continue flawlessly even if I leave the tab open in the background and the browser suspends it.

• As a user I want the UI to still be usable during a restore operation, including a loading indicator so I know that something is happening in the background.

Value

• Stability for long running operations
• No frustration and errors

Acceptance Criteria

• New web worker for restore operations
• UI is not blocked during a longer restore operation
• Loading indicator is showing during a longer restore operation (debounce ~0.5-1 second)
• Token inside the web worker is being refreshed on token renewal

Definition of ready

• Everybody needs to understand the value written in the user story
• Acceptance criteria have to be defined
• All dependencies of the user story need to be identified
• Feature should be seen from an end user perspective
• Story has to be estimated
• Story points need to be less than 20

Definition of done

• Functional requirements
  • Functionality described in the user story works
  • Acceptance criteria are fulfilled
• Quality
  • Code review happened
  • CI is green (that includes new and existing automated tests)
  • Critical code received unit tests by the developer
• Non-functional requirements
  • No sonar cloud issues