Implement Environment Variable Context Propagation carriers in api/in…#8074

Bhagirath00 wants to merge 6 commits intoopen-telemetry:mainopen-telemetry/opentelemetry-java:mainfrom

Bhagirath00:feature/env-var-propagationBhagirath00/opentelemetry-java:feature/env-var-propagationCopy head branch name to clipboard