Proposal: Config file support for instrumentor and other components

[owais]

There was some discussion to about ways to configure auto-instrumentation in #663. There was also some debate about env vars vs a config file. I don't think OpenTelemetry Python should dictate users use either env vars or a config file. I think both should be supported for end users. At the same time components shouldn't have to deal with os.environ, files or multiple config APIs. I'm proposing a fairly simple solution that allows us to have both without changing the existing config API in any way: https://docs.google.com/document/d/1SpNhP19QiaAxptDMriyIdKWtsRNXzAmPRtjl0EX14H8

This is certainly not a requirement for any feature but I think we should consider it iff we were to add support for config files.

[github-actions]

This issue was marked stale due to lack of activity. It will be closed in 30 days.

[owais]

This is irrelevant now. Was proposed a long time ago and never discussed in detail