Add db statements to linked spans

[GrzegorzDrozd]

This PR introduces a new feature to the PDO auto instrumentation that enhances the observability of database queries, specifically for clients that do not support linked spans (e.g., New Relic).

Changes:

• Added a new environment variable (OTEL_PHP_INSTRUMENTATION_PDO_DISTRIBUTE_STATEMENT_TO_LINKED_SPANS) and cfg variable (otel.instrumentation.pdo.distribute_statement_to_linked_spans).
• When enabled (true), the database statement is included in linked spans (so statement is set not only in PDO::prepare but also in PDOStatement::execute and PDOStatement::fetchAll). It will result in more data being sent, be aware that it might generate additional cost. It is disabled by default.
• This allows clients like New Relic to display the full query in the span spans that are actually taking the longest.

[welcome]

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[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: GrzegorzDrozd / name: Grzegorz Drozd (2e4bc1a, d6fb171)

[bobstrecansky]

Thank you @GrzegorzDrozd! Once you've signed the CLA we'll be able to review and merge.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.62%. Comparing base (ee99079) to head (2e4bc1a).
Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #325      +/-   ##
============================================
- Coverage     85.87%   85.62%   -0.25%     
+ Complexity     1081     1049      -32     
============================================
  Files            73       71       -2     
  Lines          4480     4231     -249     
============================================
- Hits           3847     3623     -224     
+ Misses          633      608      -25     

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Instrumentation/CodeIgniter	73.77% <ø> (ø)
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Instrumentation/MySqli	96.10% <ø> (ø)
Instrumentation/OpenAIPHP	87.31% <ø> (ø)
Instrumentation/PDO	?
Instrumentation/Psr14	77.14% <ø> (ø)
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ResourceDetectors/Container	93.02% <ø> (ø)
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Symfony	87.81% <ø> (ø)

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

see 2 files with indirect coverage changes

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[GrzegorzDrozd]

Thank you @GrzegorzDrozd! Once you've signed the CLA we'll be able to review and merge.

You mean this:

? Do i need to do anything more ?

[GrzegorzDrozd]

@brettmc Thank you for approving this PR. What's next? Failing checks are nowhere near code I changed. Am I suppose to fix them? If not then when can we expect merge and release?

[brettmc]

Failing checks are nowhere near code I changed. Am I suppose to fix them?

No, not your problem. I was going to give it a day or two to see if anybody else wants to review or provide feedback before I merge.

[GrzegorzDrozd]

@brettmc Thanks for merging :) any ETA on possible release date ?

[brettmc]

Done, was just waiting on another PR to be merged.