[WIP] Adjust the standards for proto target to align with those of Protocol Buffers.

[owent]

Fixes #3799

Changes

Please provide a brief description of the changes here.

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 PR adds CI validation to ensure OpenTelemetry C++ can be built with a different C++ standard than the protobuf dependency it uses, addressing issue #3799 where MSVC linking errors occurred when protobuf was compiled with C++17 but OpenTelemetry was built with C++20.

Key Changes:

• Adds new cmake.different_std.test CI target for both Linux (GCC) and Windows (MSVC) platforms
• Linux GCC test installs dependencies with C++17, then builds OpenTelemetry with C++23
• Windows MSVC test validates similar scenario with C++20 for OpenTelemetry

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
ci/do_ci.sh	Adds new cmake.different_std.test target for Linux/GCC that builds with C++23 STL and enables OTLP file support
ci/do_ci.ps1	Adds new cmake.different_std.test target for Windows/MSVC that builds with C++20 STL, maintainer mode, and OTLP file support
.github/workflows/ci.yml	Adds two new CI jobs: one for GCC (installs protobuf with C++17, builds with C++23) and one for MSVC (tests different C++ standards)

[Copilot]

The PowerShell script sets DWITH_STL=CXX20 (line 278) and also explicitly sets DCMAKE_CXX_STANDARD=20 (line 279). However, the bash script only sets DWITH_STL=CXX23 (line 343) without explicitly setting CMAKE_CXX_STANDARD. This inconsistency could lead to different behaviors. Consider either adding CMAKE_CXX_STANDARD to the bash script or removing it from the PowerShell script to maintain consistency, or align both to use the same C++ standard version.

Suggested change

	-DWITH_ASYNC_EXPORT_PREVIEW=ON \
	-DWITH_ASYNC_EXPORT_PREVIEW=ON \
	-DCMAKE_CXX_STANDARD=23 \

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.93%. Comparing base (f0a1da2) to head (00ca2ea).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3800   +/-   ##
=======================================
  Coverage   89.93%   89.93%           
=======================================
  Files         225      225           
  Lines        7163     7163           
=======================================
  Hits         6441     6441           
  Misses        722      722           

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