[Code health] Remove Unicode Text from Source files

[perhapsmaple]

Fixes #2706

Changes

Removed Unicode characters from API headers and opentracing-shim/src/span_shim.cc.

Escaped UTF-8 characters from test file data:

./ext/test/http/url_parser_test.cc: c program text, Unicode text, UTF-8 text
./sdk/test/metrics/instrument_metadata_validator_test.cc: c program text, Unicode text, UTF-8 text

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

[marcalff]

For UTF-8 character still present, like in:

./ext/test/http/url_parser_test.cc: c program text, Unicode text, UTF-8 text

The offending source code is:

      {"%C3%B6%C3%A0%C2%A7%C3%96abcd%C3%84", "öà§ÖabcdÄ"},

Instead of using the character ö in the expected string, which corresponds to C3B6:

U+00F6	ö	c3 b6	LATIN SMALL LETTER O WITH DIAERESIS

could the code be changed to use unicode escape sequences like \u00F6 instead, so all the code is UTF-8 clean.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.67%. Comparing base (497eaf4) to head (0a8dc8d).
Report is 86 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2707      +/-   ##
==========================================
+ Coverage   87.12%   87.67%   +0.55%     
==========================================
  Files         200      190      -10     
  Lines        6109     5853     -256     
==========================================
- Hits         5322     5131     -191     
+ Misses        787      722      -65     

Files	Coverage Δ
api/include/opentelemetry/baggage/baggage.h	97.30% <ø> (ø)
api/include/opentelemetry/context/context.h	100.00% <ø> (ø)
...pi/include/opentelemetry/context/runtime_context.h	97.50% <ø> (-0.09%)	⬇️

... and 105 files with indirect coverage changes

[marcalff]

Thanks for the fix.

See comments, to also replace UTF-8 characters present in test files.

This will affect the build when compiling with unit tests, so it is desirable to also clean test code, even if used only optionally.

[marcalff]

Instead of using the character ö in the expected string, which corresponds to C3B6:

U+00F6	ö	c3 b6	LATIN SMALL LETTER O WITH DIAERESIS

could the code be changed to use unicode escape sequences like \u00F6 instead, so all the code is UTF-8 clean.

... and of course my suggestion does not work for windows / msvc for some reason (CI failures), sorry about that.

From what I could find, windows may need a std::wstring and a L"\u00F6" literal, but since no code in opentelemetry-cpp uses wstring currently, this is likely to open a can of worms.

A possible work around is to code the UTF-8 data instead : "\xC3\xB6", please try.

If this still fails, don't waste time on it, and remove changes from the two test files, these will be fixed separately.

Thanks

[marcalff]

LGTM, thanks for the fix.