[APPSEC-55378] Extract processor context into separate file

[Strech]

Change log entry

Not needed.

What does this PR do?

This is a preparation PR which extracts Datadog::AppSec::Processor::Context into a separate file. No changes (yet 😏) to the logic or implementation were done.

Motivation:

We are going to work on those items soon and it makes sense to separate files.

Additional Notes:

None.

How to test the change?

Just CI.

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-10-24 16:24:16

Comparing candidate commit a5e63c2 in PR branch appsec-55378-extract-waf-context with baseline commit 06e050b in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 24 metrics, 2 unstable metrics.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.84%. Comparing base (06e050b) to head (a5e63c2).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4023      +/-   ##
==========================================
- Coverage   97.86%   97.84%   -0.02%     
==========================================
  Files        1319     1321       +2     
  Lines       79322    79325       +3     
  Branches     3934     3934              
==========================================
- Hits        77628    77616      -12     
- Misses       1694     1709      +15     

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[vpellan]

LGTM!

[vpellan]

I think event is a ::Hash[Symbol, untyped] according to where it's used (e.g.: https://github.com/DataDog/dd-trace-rb/blob/master/lib/datadog/appsec/contrib/rack/gateway/watcher.rb#L47), I'm not sure it is more useful than declaring it as untyped though

Suggested change

	type event = untyped
	type event = ::Hash[Symbol, untyped]

[Strech]

Maybe, I'm not sure that I fully understand the code to change it now, we have events from the WAF module too and so far they are always empty.

I think we can definitely change it as soon as we 100% sure.