feat: add IAST propagation for string' split, rsplit and splitlines

[juanjux]

Description

Add propagation for the split/rsplit/splitlines methods.

Checklist

• Change(s) are motivated and described in the PR description
• Testing strategy is described if automated tests are not included in the PR
• Risks are described (performance impact, potential for breakage, maintainability)
• Change is maintainable (easy to change, telemetry, documentation)
• Library release note guidelines are followed or label changelog/no-changelog is set
• Documentation is included (in-code, generated user docs, public corp docs)
• Backport labels are set (if applicable)
• If this PR changes the public interface, I've notified @DataDog/apm-tees.

Reviewer Checklist

• Title is accurate
• All changes are related to the pull request's stated goal
• Description motivates each change
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Change is maintainable (easy to change, telemetry, documentation)
• Release note makes sense to a user of the library
• Author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: juanjux/APPSEC-9608-string-split-rsplit-splitlines-progatation
Commit report: 4a3dc16
Test service: dd-trace-py

✅ 0 Failed, 108767 Passed, 3520 Skipped, 6m 29.82s Total duration (36m 23.12s time saved)

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-04-28 21:33:57

Comparing candidate commit bd69a86 in PR branch juanjux/APPSEC-9608-string-split-rsplit-splitlines-progatation with baseline commit bf42804 in branch main.

Found 6 performance improvements and 5 performance regressions! Performance is the same for 190 metrics, 9 unstable metrics.

scenario:httppropagationextract-invalid_span_id_header

• 🟩 max_rss_usage [-715.603KB; -432.915KB] or [-3.387%; -2.049%]

scenario:sethttpmeta-collectipvariant_exists

• 🟥 max_rss_usage [+767.817KB; +842.320KB] or [+3.679%; +4.036%]

scenario:sethttpmeta-no-collectipvariant

• 🟥 max_rss_usage [+728.965KB; +802.119KB] or [+3.493%; +3.844%]

scenario:sethttpmeta-obfuscation-disabled

• 🟩 max_rss_usage [-778.538KB; -696.022KB] or [-3.592%; -3.211%]

scenario:sethttpmeta-obfuscation-no-query

• 🟥 max_rss_usage [+718.531KB; +792.074KB] or [+3.442%; +3.794%]

scenario:sethttpmeta-obfuscation-regular-case-explicit-query

• 🟩 max_rss_usage [-969.914KB; -891.718KB] or [-4.440%; -4.082%]

scenario:sethttpmeta-obfuscation-regular-case-implicit-query

• 🟩 max_rss_usage [-947.993KB; -873.498KB] or [-4.344%; -4.003%]

scenario:sethttpmeta-useragentvariant_exists_2

• 🟩 max_rss_usage [-778.795KB; -704.776KB] or [-3.597%; -3.255%]

scenario:sethttpmeta-useragentvariant_exists_3

• 🟩 max_rss_usage [-767.178KB; -691.407KB] or [-3.545%; -3.195%]

scenario:sethttpmeta-useragentvariant_not_exists_2

• 🟥 max_rss_usage [+526.272KB; +600.537KB] or [+2.502%; +2.855%]

scenario:tracer-medium

• 🟥 max_rss_usage [+922.317KB; +991.335KB] or [+4.539%; +4.878%]

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 203 lines in your changes are missing coverage. Please review.

Project coverage is 6.61%. Comparing base (704aac0) to head (4a3dc16).
Report is 24 commits behind head on main.

Files	Patch %	Lines
tests/appsec/iast/aspects/test_split_aspect.py	0.00%	117 Missing ⚠️
ddtrace/appsec/_iast/_taint_tracking/aspects.py	0.00%	38 Missing ⚠️
tests/appsec/iast/aspects/test_str_aspect.py	0.00%	28 Missing ⚠️
tests/appsec/iast/fixtures/aspects/str_methods.py	0.00%	15 Missing ⚠️
ddtrace/appsec/_iast/_taint_tracking/__init__.py	0.00%	3 Missing ⚠️
tests/appsec/iast/aspects/test_aspect_helpers.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #9113       +/-   ##
===========================================
- Coverage   78.64%    6.61%   -72.04%     
===========================================
  Files        1254     1233       -21     
  Lines      117809   117223      -586     
===========================================
- Hits        92653     7755    -84898     
- Misses      25156   109468    +84312     

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