RUMM-3239 Fix RUM Context in Logs

[maxep]

What and why?

Fix RUM context not being attached to log when no user action exists.

How?

Allow nil values in RUM context.

Review checklist

• Feature or bugfix MUST have appropriate tests (unit, integration)
• Make sure each commit and the PR mention the Issue number or JIRA reference
• Add CHANGELOG entry for user facing changes

Custom CI job configuration (optional)

• Run unit tests
• Run integration tests
• Run smoke tests

[datadog-datadog-prod-us1]

Datadog Report

Branch report: maxep/RUMM-3239/fix-rum-context-in-logs
Commit report: 660aa75

❄️ dd-sdk-ios: 0 Failed, 1 New Flaky, 2118 Passed, 0 Skipped, 8m 44.81s Wall Time

New Flaky Tests (1)

• testWhenDataIsBeingUploaded_itPrintsUploadProgressInformation - DataUploadWorkerTests - Last Failure

  Expand for error

   
   Assertion Failure at DataUploadWorkerTests.swift:305: XCTAssertEqual failed: ("3") is not equal to ("2")
   Assertion Failure at DataUploadWorkerTests.swift:307: XCTAssertEqual failed: ("NTP time synchronization completed.
   Server time will be used for signing events (0.015s difference with device time).") is not equal to ("⏳ (ND13kzLu2a) Uploading batch...") - Batch start information should be printed to \`userLogger\`. All captured logs:
   [(level: Datadog.CoreLoggerLevel.debug, message: "NTP time synchronization completed.\nServer time will be used for signing events (0.015s difference with device time).", error: nil), (level: Datadog.CoreLoggerLevel.debug, message: "⏳ (ND13kzLu2a) Uploading batch...", error: nil), (level: Datadog.CoreLoggerLevel.debug, message: "   → (ND13kzLu2a) not delivered, will be retransmitted: JqqIwBnINC", error: nil)]
   Assertion Failure at DataUploadWorkerTests.swift:313: XCTAssertEqual failed: ("⏳ (ND13kzLu2a) Uploading batch...") is not equal to ("   → (ND13kzLu2a) not delivered, will be retransmitted: JqqIwBnINC") - Batch completion information should be printed to \`userLogger\`. All captured logs:
   [(level: Datadog.CoreLoggerLevel.debug, message: "NTP time synchronization completed.\nServer time will be used for signing events (0.015s difference with device time).", error: nil), (level: Datadog.CoreLoggerLevel.debug, message: "⏳ (ND13kzLu2a) Uploading batch...", error: nil), (level: Datadog.CoreLoggerLevel.debug, message: "   → (ND13kzLu2a) not delivered, will be retransmitted: JqqIwBnINC", error: nil)]
  

[maxep]