RUMM-2608: Use event write context for Traces

[0xnm]

What does this PR do?

This PR brings the usage of event write context (which can be retrieved by calling withWriteContext) for traces.

It is done by changing the TraceWriter so that it requests event write context for the collection of DDSpan to write.

EWC will be requests only once, so that DD context is the same for all the spans to be written.

Also introduced ContextAwareMapper and ContextAwareSerializer, because both mapping (from legacy DDSpan to SpanEvent and serialization) require DatadogContext access, and options like to create them each time inside EWC or use Pair<DatadogContext, T> as argument seemed less reasonable to me.

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 #1106 (e8b3371) into feature/sdkv2 (e201ff4) will decrease coverage by 0.29%.
The diff coverage is 90.87%.

❗ Current head e8b3371 differs from pull request most recent head 9720e9c. Consider uploading reports for the commit 9720e9c to get more accurate results

@@                Coverage Diff                @@
##           feature/sdkv2    #1106      +/-   ##
=================================================
- Coverage          82.64%   82.35%   -0.29%     
=================================================
  Files                350      351       +1     
  Lines              11301    11367      +66     
  Branches            1846     1878      +32     
=================================================
+ Hits                9339     9361      +22     
- Misses              1396     1432      +36     
- Partials             566      574       +8     

Impacted Files	Coverage Δ
...n/com/datadog/android/core/internal/CoreFeature.kt	91.09% <ø> (-0.35%)	⬇️
...in/com/datadog/android/core/internal/SdkFeature.kt	88.18% <ø> (ø)
...atadog/android/log/internal/domain/LogGenerator.kt	80.00% <ø> (-3.33%)	⬇️
...og/android/v2/core/internal/NoOpContextProvider.kt	3.57% <0.00%> (-0.78%)	⬇️
.../android/v2/log/internal/storage/LogsDataWriter.kt	60.00% <60.00%> (ø)
.../android/error/internal/DatadogExceptionHandler.kt	81.08% <84.62%> (-4.63%)	⬇️
...in/com/datadog/android/log/internal/LogsFeature.kt	87.10% <85.96%> (-12.90%)	⬇️
...g/android/log/internal/logger/DatadogLogHandler.kt	90.91% <86.96%> (-0.76%)	⬇️
.../src/main/kotlin/com/datadog/android/log/Logger.kt	94.02% <93.33%> (+0.12%)	⬆️
...tadog/android/tracing/internal/data/TraceWriter.kt	95.83% <95.65%> (-4.17%)	⬇️
... and 26 more

[mariusc83]

Nicely done. Lgtm !!