RUMM-2448: Add variant tag to logs

[0xnm]

What does this PR do?

THIS PR TARGETS 1.14.0 RELEASE BRANCH

This change adds variant to ddTags of Logs events to be able to support stacktraces de-obfuscation in Logs dashboard.

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 #1025 (aca8639) into release/1.14.0 (291142c) will increase coverage by 0.10%.
The diff coverage is 100.00%.

@@                Coverage Diff                 @@
##           release/1.14.0    #1025      +/-   ##
==================================================
+ Coverage           83.03%   83.13%   +0.10%     
==================================================
  Files                 270      270              
  Lines                9241     9249       +8     
  Branches             1486     1488       +2     
==================================================
+ Hits                 7673     7689      +16     
+ Misses               1158     1152       -6     
+ Partials              410      408       -2     

Impacted Files	Coverage Δ
...in/kotlin/com/datadog/android/log/LogAttributes.kt	0.00% <ø> (ø)
...n/com/datadog/android/core/internal/CoreFeature.kt	91.53% <100.00%> (+0.04%)	⬆️
...adog/android/error/internal/CrashReportsFeature.kt	100.00% <100.00%> (ø)
.../src/main/kotlin/com/datadog/android/log/Logger.kt	95.97% <100.00%> (+0.03%)	⬆️
...atadog/android/log/internal/domain/LogGenerator.kt	99.00% <100.00%> (+0.05%)	⬆️
.../android/rum/internal/monitor/DatadogRumMonitor.kt	92.86% <0.00%> (-0.60%)	⬇️
...android/rum/internal/ndk/DatadogNdkCrashHandler.kt	88.04% <0.00%> (ø)
...rc/main/java/com/datadog/opentracing/DDTracer.java	56.49% <0.00%> (+0.42%)	⬆️
...ain/java/com/datadog/opentracing/PendingTrace.java	60.34% <0.00%> (+1.72%)	⬆️
...droid/rum/tracking/ActivityViewTrackingStrategy.kt	88.46% <0.00%> (+1.92%)	⬆️
... and 2 more