Set required attribute of DB_SYSTEM

[cedricziel]

This change introduces a default value for db.system, to satisfy the opentelemetry specification.

It also tracks a statement <-> PDO mapping based on the object ids so we can annotate the correct attributes on statement spans.

[codecov]

Codecov Report

Merging #181 (34e7a63) into main (8f69ac2) will increase coverage by 2.14%.
The diff coverage is 58.33%.

❗ Current head 34e7a63 differs from pull request most recent head 63f30b6. Consider uploading reports for the commit 63f30b6 to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #181      +/-   ##
============================================
+ Coverage     32.62%   34.76%   +2.14%     
- Complexity      783      791       +8     
============================================
  Files            69       70       +1     
  Lines          2970     3017      +47     
============================================
+ Hits            969     1049      +80     
+ Misses         2001     1968      -33     

Flag	Coverage Δ
7.4	46.08% <ø> (ø)
8.0	34.83% <ø> (ø)
8.1	34.87% <ø> (ø)
8.2	34.71% <58.33%> (+2.14%)	⬆️

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Impacted Files	Coverage Δ
src/Instrumentation/PDO/src/PDOInstrumentation.php	33.33% <29.03%> (+33.33%)	⬆️
...rc/Instrumentation/PDO/src/PDOAttributeTracker.php	89.65% <89.65%> (ø)

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[brettmc]

Is everybody happy for me to merge this?

[lstrojny]

@brettmc sure, just a small cosmetics issue from my side

[cedricziel]

I'm good