Update go lockfile generator to use output from `go list`

[ejortega]

Changes the go lockfile generator to use the output of go list -m -json all from the previous go.sum generation using go get -d.

Closes https://github.com/phylum-dev/cli/issues/1396

Checklist

• [x] Does this PR have an associated issue (i.e., closes #<issueNum> in description above)?
• [x] Have you ensured that you have met the expected acceptance criteria?
• [x] Have you created sufficient tests?
• [x] Have you updated all affected documentation?
• [x] Have you updated CHANGELOG.md (or extensions/CHANGELOG.md), if applicable

[ejortega]

Closing this PR as we'll be parsing the go.mod and go.sum directly.