Promote OtelEncodingUtils to io.opentelemetry.api.impl (#6970)

[rooks-ns]

Part of #6970.

Promotes OtelEncodingUtils from io.opentelemetry.api.internal to io.opentelemetry.api.impl to eliminate cross-artifact internal package sharing across 5 downstream modules, and unexempts opentelemetry-sdk-profiles in NoSharedInternalCodeTest.

Changes

• OtelEncodingUtils: Moved from io.opentelemetry.api.internal to io.opentelemetry.api.impl in :api:all.
• Callers: Updated imports in :api:all, :sdk:profiles, :sdk:trace, :exporters:common, :exporters:otlp:common, :exporters:otlp:profiles, and :sdk-extensions:incubator.
• NoSharedInternalCodeTest: Removed opentelemetry-sdk-profiles from exemptions.

[otelbot]

⚠️ API changes detected — additional maintainer review required

@jack-berg @jkwatson

This PR modifies the public API surface area of the following module(s):

• opentelemetry-api

Please review the changes in docs/apidiffs/current_vs_latest/ carefully before approving.

[opentelemetry-pr-dashboard]

Pull request dashboard status

Waiting on maintainers · refreshed 2026-10-19 19:33 UTC

Merge when ready.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.40%. Comparing base (b32298a) to head (dcb2404).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8929      +/-   ##
============================================
- Coverage     90.40%   90.40%   -0.01%     
- Complexity    10898    10903       +5     
============================================
  Files          1015     1016       +1     
  Lines         29843    29852       +9     
  Branches       3896     3897       +1     
============================================
+ Hits          26981    26989       +8     
  Misses         1910     1910              
- Partials        952      953       +1     

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[jack-berg]

FYI, I pushed a commit to address a few lingering concerns:

• *.impl.OtelEncodingUtils duplicates the *.internal.OtelEncodingUtils content. Switched to a delegation model.
• Changed the public class name to Base16EncodingUtils, better reflecting the scope of the APIs and avoiding a situation where we have to use the FQCN when delegating to *.internalOtelEncodingUtils