[PROTO] Upgrade to opentelemetry-proto v1.1.0

[marcalff]

Fixes #2487
Prepare for #2283

Changes

Please provide a brief description of the changes here.

• Upgrade opentelemetry-proto to v1.1.0
• Send trace flags in OtlpRecordable::SetTraceFlags()
• Add an IsRandom() property in class IdGenerator.
• Prepare the code to collect and send the IsRandom trace flags.

Currently, the specs complies with W3C Trace Context version 1, so that IsRandom is ignored.

When adoption of W3C Trace Context version 2 is effective, the implementation of Tracer::StartSpan() will need to change 1 line of code (using kAllW3CTraceContext2Flags instead of kAllW3CTraceContext1Flags) to complete the implementation of #2283

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f084fbc) 87.06% compared to head (cbeb840) 87.09%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2488      +/-   ##
==========================================
+ Coverage   87.06%   87.09%   +0.04%     
==========================================
  Files         199      200       +1     
  Lines        6087     6103      +16     
==========================================
+ Hits         5299     5315      +16     
  Misses        788      788              

Files	Coverage Δ
api/include/opentelemetry/trace/trace_flags.h	100.00% <ø> (ø)
sdk/include/opentelemetry/sdk/trace/id_generator.h	100.00% <100.00%> (ø)
...include/opentelemetry/sdk/trace/multi_recordable.h	89.40% <100.00%> (+0.69%)	⬆️
...lude/opentelemetry/sdk/trace/random_id_generator.h	100.00% <100.00%> (ø)
sdk/include/opentelemetry/sdk/trace/recordable.h	68.75% <ø> (ø)
sdk/include/opentelemetry/sdk/trace/span_data.h	98.69% <100.00%> (+0.02%)	⬆️
sdk/src/trace/span.cc	89.78% <100.00%> (+0.12%)	⬆️
sdk/src/trace/tracer.cc	82.46% <100.00%> (+2.46%)	⬆️

[lalitb]

Thanks.

[dbolduc]

This was a breaking change. Why not provide a no-op default implementation?

  virtual void SetTraceFlags(opentelemetry::trace::TraceFlags flags) noexcept {};