Unify builders across signals

[stormshield-fabs]

Fixes #1527 #2164

Changes

The consensus reached during the SIG meeting is that we'd like to unify the builder APIs across signals, limit duplication and keep our traits object-safe. Proposed changed :

• remove the Logger and Tracer builders that were only used to wrap the InstrumentationLibrary builder
• remove the deprecated versioned_ methods on providers
• reduce the public API to Provider::signal(name: &str) and Provider::library_signal(library: Arc<InstrumentationLibrary>)

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Attention: Patch coverage is 78.52349% with 32 lines in your changes missing coverage. Please review.

Project coverage is 79.2%. Comparing base (ea4b5e4) to head (a6bd2db).

Files with missing lines	Patch %	Lines
opentelemetry-zipkin/src/exporter/mod.rs	0.0%	10 Missing ⚠️
opentelemetry-stdout/src/trace/exporter.rs	0.0%	4 Missing ⚠️
opentelemetry/src/global/trace.rs	57.1%	3 Missing ⚠️
opentelemetry-proto/src/transform/trace.rs	60.0%	2 Missing ⚠️
opentelemetry-sdk/src/logs/log_emitter.rs	83.3%	2 Missing ⚠️
opentelemetry-sdk/src/logs/log_processor.rs	88.2%	2 Missing ⚠️
opentelemetry-sdk/src/trace/tracer.rs	66.6%	2 Missing ⚠️
opentelemetry/src/global/metrics.rs	0.0%	2 Missing ⚠️
opentelemetry-proto/src/transform/common.rs	50.0%	1 Missing ⚠️
opentelemetry-proto/src/transform/logs.rs	66.6%	1 Missing ⚠️
... and 3 more

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2220     +/-   ##
=======================================
+ Coverage   79.1%   79.2%   +0.1%     
=======================================
  Files        121     121             
  Lines      21082   20849    -233     
=======================================
- Hits       16680   16522    -158     
+ Misses      4402    4327     -75     

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[stormshield-fabs]

There were some concerns about having Arc in the library_signal APIs, but someone also mentioned we want to avoid unnecessary copies. We could hide the Arc inside the InstrumentationLibrary if needed.

[cijothomas]

Left few comments but looks good overall.
Please check the comments and see if they make sense.

[cijothomas]

There were some concerns about having Arc in the library_signal APIs, but someone also mentioned we want to avoid unnecessary copies. We could hide the Arc inside the InstrumentationLibrary if needed.

yes I suggest to hide Arc inside.

[cijothomas]

@stormshield-fabs Thanks a lot! I think the following are to be addressed before merge. We also need to write a migration guide in the PR description showing before/after, so users can easily (relatively) react to this.

Lets keep InstrumentationScope simple, and accept the perf cost now, given it is infrequent operation.
#2220 (comment)

Rename library-signal to something like signal_with_scope/better names.
#2220 (comment)