[APPSEC-57237] Handle business logic events

[Strech]

What does this PR do?

Adds handling of business logic events to be able to finish fingerprinting feature.

Motivation:

The last bits of fingerprinting is to act on business logic events that produced during sign in via auto-instrumentation or SDK.

Change log entry

Yes. AppSec: Add session tracking and fingerprinting support to devise and rails contribs.

Additional Notes:

I would like to restructure integration tests to better separate specifically contrib tests from general logic tests. Hence you would see test in the rack contrib (for now)

Second - we have an issue in libddwaf-rb which converts provided nil values into empty strings. Another option is to give a value invalid which doesn't make much sense, but it is what it is.

This is what's new in system-tests

How to test the change?

CI + ST

[datadog-datadog-prod-us1]

Datadog Summary

❌ Code Quality    ✅ Code Security    ✅ Dependencies

Test Optimization Report

Branch report: appsec-57237-add-business-events-handling
Commit report: 59616ae
Test service: dd-trace-rb

✅ 0 Failed, 21256 Passed, 1373 Skipped, 3m 57.94s Total Time

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 95.83333% with 3 lines in your changes missing coverage. Please review.

Project coverage is 97.77%. Comparing base (1edbedf) to head (28cc8a2).

Files with missing lines	Patch %	Lines
lib/datadog/appsec/monitor/gateway/watcher.rb	83.33%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4644      +/-   ##
==========================================
- Coverage   97.77%   97.77%   -0.01%     
==========================================
  Files        1415     1416       +1     
  Lines       86561    86631      +70     
  Branches     4386     4391       +5     
==========================================
+ Hits        84633    84701      +68     
- Misses       1928     1930       +2     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2025-05-13 13:39:58

Comparing candidate commit baaef72 in PR branch appsec-57237-add-business-events-handling with baseline commit 15a6b5f in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 31 metrics, 2 unstable metrics.