[BUILD] Add more export symbols

[owent]

Changes

• Add more symbols for dll to make all CI jobs in [BUILD] Rename cmake options with prefix OTELCPP_  #4268 pass.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[Copilot]

Pull request overview

This pull request updates the Windows DLL export symbol allowlist used by the ext_dll build to ensure additional SDK/exporter APIs are exported from opentelemetry_cpp.dll, addressing CI failures introduced by recent build-option changes.

Changes:

• Export additional SDK factory APIs and option types (batch span/log processor support).
• Export lifecycle APIs (ForceFlush/Shutdown) for SDK providers (trace/logs/metrics).
• Export additional OTLP client/runtime-option symbols (gRPC client factory; HTTP runtime option structs) and GlobalLogHandler::SetLogLevel.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.63%. Comparing base (3603e13) to head (7fa0131).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4461   +/-   ##
=======================================
  Coverage   82.63%   82.63%           
=======================================
  Files         512      512           
  Lines       20138    20138           
=======================================
  Hits        16639    16639           
  Misses       3499     3499           

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[marcalff]

LGTM.

Thanks @owent