* Introduce new AuditEntryService
- Moved logic related to the IAuditEntryRepository from the AuditService to the new service
- Introduced new Async methods
- Using ids (for easier transition from the previous Write method)
- Using keys
- Moved and updated integration tests related to the audit entries to a new test class `AuditEntryServiceTests`
- Added unit tests class `AuditEntryServiceTests` and added a few unit tests
- Added migration to add columns for `performingUserKey` and `affectedUserKey` and convert existing user ids
- Adjusted usages of the old AuditService.Write method to use the new one (mostly notification handlers)
* Audit service rework
- Added new async and paged methods
- Marked (now) redundant methods as obsolete
- Updated all of the usages to use the non-obsolete methods
- Added unit tests class `AuditServiceTests` and some unit tests
- Updated existing integration test
* Apply suggestions from code review
* Small improvement
* Update src/Umbraco.Core/Services/AuditService.cs
* Some minor adjustments following the merge
* Delete unnecessary file
* Small cleanup on the tests
* Refactor jobs from HostedServices into BackgroundJobs
* Clean up generics and DI setup
* Add RecurringBackgroundJob Unit Tests
* Add ServiceCollection helper
* Add Obsolete attributes
* Add Notification Classes
* Add UnitTests for RecurringBackgroundJob HostedService
* Add NotificationEvents
* Add state to notifications
* Update UnitTests
* Add Obsolete Attributes to old hosted service classes
* Updated xmldoc in IRecurringBackgroundJob.cs
* Update Obsolete attribute messages to indicate classes will be removed in Umbraco 14
(cherry picked from commit c30ffa9ac3)
