Remove opentelemetry-exporter-otlp-proto-common dependency

[sfc-gh-jopel]

This PR

• Internalizes some encoding logic from opentelemetry-exporter-otlp-proto-common under the directory src/snowflake/internal/opentelemetry/exporter/**
• Modifies the above logic to use the custom serialization structures introduced in Add code generator for otel proto #39
• Updates tests to check for equality of serialized bytes rather than PB2 objects, since the new code only produces bytes
• Adds a micro-benchmark to compare encoding performance of the original library and the new approach under the benchmarks/** directory

Todo in future PRs:

• Add import time and memory benchmarks
• Add branching / try..except import to use the original opentelemetry-exporter-otlp-proto-common if it is present in the runtime instead of the custom logic
• Add a step to the release script & Jenkins job to test the .conda / .tar.bz2 package in a conda environment end to end
• Release v0.6.0

------------------------------------------------------------------------------
Benchmark                                    Time             CPU   Iterations
------------------------------------------------------------------------------
test_bm_serialize_logs_data_4MB      218404625 ns    218404667 ns            3
test_bm_pb2_serialize_logs_data_4MB  279917764 ns    279916000 ns            3
test_bm_serialize_logs_data              35747 ns        35747 ns        19741
test_bm_pb2_serialize_logs_data          41652 ns        41651 ns        16939
test_bm_serialize_metrics_data           59798 ns        59798 ns        11593
test_bm_pb2_serialize_metrics_data       70521 ns        70521 ns         9815
test_bm_serialize_traces_data            47156 ns        47156 ns        14807
test_bm_pb2_serialize_traces_data        59690 ns        59690 ns        11766

https://docs.google.com/document/d/1plfwWBVRJGzU5dl3kph4HWwgnxBc8TJm0JCyanCdJuM/edit?usp=sharing

[sfc-gh-sili]

@sfc-gh-bdrutu
Do you have any advice how we should update this copyright?
Is it okay to simply change it to Snowflake since Apache Liscense (https://en.wikipedia.org/wiki/Apache_License) "allows users to use, modify, and distribute software for any purpose"?

With a note like
"Adapted from github.com/opentelemetry/opentelemetry-proto/xxxxx/init.py"

[sfc-gh-sili]

Let's rename this API since we do different thing from what opentelemetry is doing.