Resource auto-detection

[mwear]

While not formally specified by the Resource spec, we are probably going to want:

• Resource initialization from environment variables
  • related: Ambiguity interpreting keys and values from environment variables opentelemetry-specification#501
• Resource auto-detection
  • container
  • cloud environment

[mayurkale22]

@mwear Can we close this issue via #899?

[mwear]

Yes!