Remove Cow from InstrumentationScope

[stormshield-fabs]

Fixes #2246

Changes

Removed the InstrumentationScope attributes from the public API and replaced them with getters.

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)

[cijothomas]

From Community Call:

1. Lets keep builder as-is (i.e accept Cow.. )
2. Hide fields from InstrumentationScope and offer pub getters.

[codecov]

Codecov Report

Attention: Patch coverage is 60.71429% with 44 lines in your changes missing coverage. Please review.

Project coverage is 79.5%. Comparing base (0b716a7) to head (7a198ae).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
opentelemetry-sdk/src/metrics/meter.rs	0.0%	17 Missing ⚠️
opentelemetry-stdout/src/trace/exporter.rs	0.0%	7 Missing ⚠️
opentelemetry-stdout/src/metrics/exporter.rs	0.0%	4 Missing ⚠️
opentelemetry-proto/src/transform/common.rs	57.1%	3 Missing ⚠️
opentelemetry-stdout/src/common.rs	0.0%	3 Missing ⚠️
opentelemetry-proto/src/transform/logs.rs	33.3%	2 Missing ⚠️
opentelemetry-proto/src/transform/metrics.rs	0.0%	2 Missing ⚠️
opentelemetry-proto/src/transform/trace.rs	0.0%	2 Missing ⚠️
opentelemetry-sdk/src/metrics/instrument.rs	60.0%	2 Missing ⚠️
opentelemetry-sdk/src/trace/tracer.rs	0.0%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2275     +/-   ##
=======================================
- Coverage   79.5%   79.5%   -0.1%     
=======================================
  Files        121     121             
  Lines      20974   20978      +4     
=======================================
+ Hits       16684   16687      +3     
- Misses      4290    4291      +1     

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[utpilla]

Looks good with a CHANGELOG entry.