implement OTel bridge

[stuartnelson3]

closes #1140

[stuartnelson3]

This is heavily annotated with TODO's and questions. Comments welcome!

[apmmachine]

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• Start Time: 2022-09-07T17:20:36.308+0000

• Duration: 3 min 50 sec

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• Description: approval-list/elastic/apm-agent-go.yml

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• Description: githubApiCall: The REST API call https://api.github.com/orgs/elastic/members/stuartnelson3 return the message : java.lang.Exception: httpRequest: Failure connecting to the service https://api.github.com/orgs/elastic/members/stuartnelson3 : httpRequest: Failure connecting to the service https://api.github.com/orgs/elastic/members/stuartnelson3 : Code: 404Error: {"message":"User does not exist or is not a member of the organization","documentation_url":"https://docs.github.com/rest/reference/orgs#check-organization-membership-for-a-user"}

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[stuartnelson3]

still need to look into https://github.com/elastic/apm/blob/main/specs/agents/tracing-api-otel.md#compatibility-mapping, but i think this is ready for another review

[stuartnelson3]

@axw can we take a look at this next week? I implemented the wrapper methods for span and transaction like you mentioned to me, but I'm wondering if I'm misunderstanding something because I don't have all of the wrapper structs that you implement.

[apmmachine]

:globe_with_meridians: Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (59/59)	:green_heart:
Files	99.346% (152/153)	:+1:
Classes	96.812% (334/345)	:+1: 0.558
Methods	90.746% (961/1059)	:+1: 0.472
Lines	82.704% (11074/13390)	:+1: 0.427
Conditionals	100.0% (0/0)	:green_heart:

[simitt]

Closing this for now as we are currently not working on this feature.