Bump OTLP proto files to 1.1.0

[Kielek]

Changes

Bump OTLP proto files to 1.1.0.

Important changes

Add flags field to Span and Span/Link for W3C-specified Trace Context flags in open-telemetry/opentelemetry-proto#503

I think that support for this is good candidate for separate issue.

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• [ ] Unit tests added/updated
• [ ] Appropriate CHANGELOG.md files updated for non-trivial changes
• [ ] Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6250307) 83.38% compared to head (1a852b7) 83.16%.
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5215      +/-   ##
==========================================
- Coverage   83.38%   83.16%   -0.23%     
==========================================
  Files         297      271      -26     
  Lines       12531    11956     -575     
==========================================
- Hits        10449     9943     -506     
+ Misses       2082     2013      -69     

Flag	Coverage Δ
unittests	?
unittests-Solution-Experimental	82.84% <100.00%> (?)
unittests-Solution-Stable	83.13% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/OpenTelemetry.Api/Baggage.cs	100.00% <100.00%> (ø)

... and 32 files with indirect coverage changes