bump protobuf to 0.19, handle grpc partial success

[brettmc]

Update protobuf files to 0.19
Handle gRPC partial success on export
Add logging to grpc examples.
Fix a race condition in one of the smoke tests

This addresses the gRPC requirement for #802 but not http.

[codecov]

Codecov Report

Merging #806 (5e56347) into main (0f30849) will increase coverage by 1.85%.
The diff coverage is 100.00%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #806      +/-   ##
============================================
+ Coverage     81.03%   82.88%   +1.85%     
- Complexity     1825     1829       +4     
============================================
  Files           225      225              
  Lines          4687     4697      +10     
============================================
+ Hits           3798     3893      +95     
+ Misses          889      804      -85     

Flag	Coverage Δ
7.4	82.89% <100.00%> (+1.86%)	⬆️
8.0	82.91% <100.00%> (+1.85%)	⬆️
8.1	82.91% <100.00%> (+1.85%)	⬆️

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Impacted Files	Coverage Δ
src/Contrib/OtlpGrpc/Exporter.php	91.42% <100.00%> (+1.26%)	⬆️
src/SDK/Trace/Behavior/HttpSpanExporterTrait.php	93.61% <100.00%> (+0.13%)	⬆️
src/SDK/Trace/Span.php	94.23% <0.00%> (+81.73%)	⬆️

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[Nevay]

Unblocks #738.

[Nevay]

OTLP/HTTP has to handle partial success responses too.

[brettmc]

OTLP/HTTP has to handle partial success responses too

Agreed. This has not yet been implemented in the otel collector (open-telemetry/opentelemetry-collector#5816 is the feature request), and currently otlp/http always returns an empty response.
I'll change this PR so that it doesn't close #802, I think we should wait until there's a protobuf response from the collector to work with...

[brettmc]

more segfault. I'll be offline for a couple of days, will look in to this later. Both mockery and phpunit mock objects segfault in much the same way.