RUM-14902: Track GraphQL errors

[kikoveiga]

What does this PR do?

• Track GraphQL errors on DatadogInterceptor for OkHttp requests.
• Create GraphQLExtractor with 2 main functions: extractGraphQLAttributes (already existing logic, moved from DatadogInterceptor for better separation of concerns) & extractGraphQLErrors (new logic). This is a reusable extraction in rum module that can be reused in the future with other networking libraries (no coupling with OkHttp).
• Create OkHttpGraphQLAdapter to encapsulate some already existing logic and delegate to the class above.
• Some cleanup (create StringExt on internal module to reuse String.toBase64 & String.fromBase64 extension functions).

Motivation

GraphQL APIs return HTTP 200 regardless of succeeding or not. Errors are reported inside the response body's errors array rather than through HTTP status codes.

Now these errors are properly caught, allowing customers to detect GraphQL failures that would otherwise go unnoticed.

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

❌ Patch coverage is 69.00000% with 31 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.47%. Comparing base (61409f2) to head (0395da9).

Files with missing lines	Patch %	Lines
...id/okhttp/internal/graphql/OkHttpGraphQLAdapter.kt	53.19%	21 Missing and 1 partial ⚠️
...va/com/datadog/android/internal/utils/StringExt.kt	0.00%	7 Missing ⚠️
...tadog/android/rum/internal/net/GraphQLExtractor.kt	94.59%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3275      +/-   ##
===========================================
- Coverage    71.62%   71.47%   -0.15%     
===========================================
  Files          942      945       +3     
  Lines        34811    34872      +61     
  Branches      5899     5906       +7     
===========================================
- Hits         24933    24924       -9     
- Misses        8241     8288      +47     
- Partials      1637     1660      +23     

Files with missing lines	Coverage Δ
...datadog/android/apollo/DatadogApolloInterceptor.kt	93.10% <ø> (-0.44%)	⬇️
...n/com/datadog/android/okhttp/DatadogInterceptor.kt	80.56% <100.00%> (+5.20%)	⬆️
...tadog/android/rum/internal/net/GraphQLExtractor.kt	94.59% <94.59%> (ø)
...va/com/datadog/android/internal/utils/StringExt.kt	0.00% <0.00%> (ø)
...id/okhttp/internal/graphql/OkHttpGraphQLAdapter.kt	53.19% <53.19%> (ø)

... and 33 files with indirect coverage changes

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