Improve extensions performance & add OpenTelemetry

[rafalp]

This PR removes separate ExtensionSync and synchronous extensions, making extensions work in both async and sync context based on next_ being coroutine function or not.

Fixes #649

TODO

• OpenTracing
• OpenTelemetry
• ApolloTracing (needs test for async and sync context)
• Update benchmarks

[codecov]

Codecov Report

Merging #1091 (3b5d226) into master (7e2c2b9) will decrease coverage by 0.44%.
The diff coverage is 92.36%.

@@            Coverage Diff             @@
##           master    #1091      +/-   ##
==========================================
- Coverage   98.24%   97.81%   -0.44%     
==========================================
  Files         115      115              
  Lines        7511     7770     +259     
==========================================
+ Hits         7379     7600     +221     
- Misses        132      170      +38     

Impacted Files	Coverage Δ
ariadne/contrib/tracing/copy_args.py	0.00% <0.00%> (ø)
tests/conftest.py	94.21% <90.90%> (-1.89%)	⬇️
ariadne/contrib/tracing/utils.py	96.29% <93.10%> (-3.71%)	⬇️
ariadne/contrib/tracing/opentelemetry.py	96.20% <96.20%> (ø)
ariadne/contrib/tracing/opentracing.py	98.61% <97.91%> (+2.82%)	⬆️
ariadne/contrib/tracing/apollotracing.py	91.66% <100.00%> (+2.95%)	⬆️
ariadne/types.py	94.20% <100.00%> (+0.69%)	⬆️
tests/asgi/test_configuration.py	100.00% <100.00%> (ø)
tests/asgi/test_query_execution.py	98.88% <100.00%> (ø)
tests/tracing/snapshots/snap_test_apollotracing.py	100.00% <100.00%> (ø)
... and 5 more

... and 2 files with indirect coverage changes

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[rafalp]

Thanks for your feedback, @dacevedo12, I've did some tweaks.