Audit service rework (#19346)

* 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

tests/Umbraco.Tests.UnitTests/Umbraco.Infrastructure/BackgroundJobs/Jobs/LogScrubberJobTests.cs

@@ -68,5 +68,5 @@ public class LogScrubberJobTests
     private void VerifyLogsScrubbed() => VerifyLogsScrubbed(Times.Once());
 
     private void VerifyLogsScrubbed(Times times) =>
-        _mockAuditService.Verify(x => x.CleanLogs(It.Is<int>(y => y == MaxLogAgeInMinutes)), times);
+        _mockAuditService.Verify(x => x.CleanLogsAsync(It.Is<int>(y => y == MaxLogAgeInMinutes)), times);
 }