This code is not plumbed through yet, but it provides the core
infrastructure needed to detect the proper GCP environment resources
needed to set up the labels/attributes/resources for stats, tracing and
logging.
Details on how the various environment resources are setup has been
derived by looking at java's cloud logging library and OpenTelemetry's
future plans. (Could be better explained in an offline review since some
links are internal).
Requesting @veblush for a full review and @markdroth for a structural
review.
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Yash Tibrewal