feat(appsec): add auto_user_instrum remote config capabilities

[Leiyks]

Description

Enable remote configs related to the auto_user_instrumentation mode according to the following RFC.

The following changes have been implemented:

• Helper: Add a new config aggregator for ASM_FEATURES to allow single file parsing in the listener.
• Helper/Extension: Add the new settings field in the requests_(init | exec | shutdown) responses to communicate parameters.
• Extension: Parsing methods for the additional settings field and new mechanism to get the auto_user_instrumentation mode.

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

Related Jiras: APPSEC-53750

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 73.46939% with 13 lines in your changes missing coverage. Please review.

Project coverage is 73.06%. Comparing base (368a541) to head (864cab2).
Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
appsec/src/extension/commands_helpers.c	66.66%	5 Missing and 3 partials ⚠️
appsec/src/extension/user_tracking.c	80.00%	2 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3079      +/-   ##
============================================
+ Coverage     73.04%   73.06%   +0.02%     
  Complexity     2792     2792              
============================================
  Files           139      139              
  Lines         15284    15330      +46     
  Branches       1047     1063      +16     
============================================
+ Hits          11164    11201      +37     
- Misses         3567     3572       +5     
- Partials        553      557       +4     

Flag	Coverage Δ
appsec-extension	68.46% <73.46%> (+0.17%)	⬆️
tracer-php	74.85% <ø> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
appsec/src/extension/user_tracking.c	73.43% <80.00%> (+2.68%)	⬆️
appsec/src/extension/commands_helpers.c	63.72% <66.66%> (+1.15%)	⬆️

... and 1 file with indirect coverage changes

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[pr-commenter]

Benchmarks [ appsec ]

Benchmark execution time: 2025-02-21 14:15:57

Comparing candidate commit 864cab2 in PR branch leiyks-rc-user-instrum-mode with baseline commit 368a541 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 12 metrics, 0 unstable metrics.

[Anilm3]

Some comments, the only critical issue is on the listener.

[Anilm3]

lgtm