Bump minimum supported Go version to 1.17

[jlvoiseux]

Motivation / Summary

The goal of this pull request is to bump the minimum Go version supported by the extension codebase to 1.17. This bump has the following perks:

• Alignment with the APM Server
• Resolve make check-licenses fails #163, tied to the check-licenses, update-licenses and lint make targets. These targets rely on the use of go install outside of a module-aware context, which is only fully possible as of Go 1.17.
• Ease the implementation of the metrics, as Unix.Milliseconds() and Unix.Microseconds() are only available in Go 1.17 (see commits 577e296 and c8e23cb).

This PR aims to track the discussion / changes necessary to perform the bump. The .Jenkinsfile and go.mod have been updated in the initial commits.

[ghost]

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• Start Time: 2022-03-30T16:26:35.222+0000

• Duration: 7 min 21 sec

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Test	Results
Failed	0
Passed	160
Skipped	4
Total	164

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[trentm]

LGTM, but I'm not an experience go dev. :)