RUM-3905: Use custom naming for threads created inside SDK

[0xnm]

What does this PR do?

This PR introduces custom ThreadFactory for the threads created by SDK. Its only purpose is to name them in format datadog-{context}-threadN, where context may be feature track, etc.

This will give us a better visibility in telemetry (the necessary attribute was added for the executor-related events) and also allows to better navigate profiling data.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[codecov-commenter]

Codecov Report

Merging #1987 (18967d7) into develop (ebf7542) will decrease coverage by 0.02%.
Report is 4 commits behind head on develop.
The diff coverage is 85.71%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1987      +/-   ##
===========================================
- Coverage    83.68%   83.66%   -0.02%     
===========================================
  Files          487      488       +1     
  Lines        17736    17770      +34     
  Branches      2663     2663              
===========================================
+ Hits         14842    14867      +25     
- Misses        2167     2178      +11     
+ Partials       727      725       -2     

Files	Coverage Δ
...in/com/datadog/android/core/NoOpInternalSdkCore.kt	9.09% <ø> (ø)
...ore/internal/thread/BackPressureExecutorService.kt	44.44% <100.00%> (+2.14%)	⬆️
...core/internal/thread/BackPressuredBlockingQueue.kt	95.45% <100.00%> (+0.58%)	⬆️
...droid/core/internal/thread/DatadogThreadFactory.kt	100.00% <100.00%> (ø)
...rum/src/main/kotlin/com/datadog/android/rum/Rum.kt	91.67% <100.00%> (ø)
...lin/com/datadog/android/rum/internal/RumFeature.kt	91.74% <100.00%> (-1.83%)	⬇️
...nal/tracking/AndroidXFragmentLifecycleCallbacks.kt	94.59% <100.00%> (+0.31%)	⬆️
...nternal/tracking/OreoFragmentLifecycleCallbacks.kt	90.00% <100.00%> (+0.53%)	⬆️
...droid/rum/tracking/ActivityViewTrackingStrategy.kt	87.50% <100.00%> (-2.50%)	⬇️
...ain/kotlin/com/datadog/android/core/DatadogCore.kt	81.98% <0.00%> (ø)
... and 2 more

... and 24 files with indirect coverage changes