Use the `go.sum` parser as the default lockfile format for golang

Updates the lockfile detection to ignore go.mod files and default to the go.sum parser.

If the go.sum is missing, the go.mod file is recognized and can be parsed if the go directive is >= 1.17.

If the go directive criteria is not satisfied, the user will receive a message that the lockfile generation is required.

❯ phylum analyze -p test

❗ Could not parse manifest: Parsing "go.mod" requires lockfile generation, but it was disabled

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