contrib: add go.mod to isolate contribs gqlgen, httptreemux, go-elasticsearch, cloud.google.com/go/pubsub.v1, hashicorp/consul & hashicorp/vault

[darccio]

What does this PR do?

Isolates the following contribs as independent modules:

• 99designs/gqlgen
• dimfeld/httptreemux.v5
• elastic/go-elasticsearch.v6
• cloud.google.com/go/pubsub.v1
• hashicorp/consul
• hashicorp/vault

This will be done for each contrib, and this is a first PR to validate the approach. Next PRs will consist of multiple contribs.

Motivation

Security scanners yield false positives, informing vulnerable versions that are present in the go.mod but not compiled into the final binary.

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.

For Datadog employees:

• If this PR touches code that handles credentials of any kind, such as Datadog API keys, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[pr-commenter]

Benchmarks

Benchmark execution time: 2023-11-22 12:03:50

Comparing candidate commit 6848485 in PR branch dario.castane/AIT-8717/isolate-contribs-batch-1 with baseline commit d9ad3a9 in branch v2-dev.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 39 metrics, 2 unstable metrics.

[RomainMuller]

Makes me wonder if this should also add a go.work file at the repository root referencing all those modules (and the root itself), for improved IDE experience?

[darccio]

Makes me wonder if this should also add a go.work file at the repository root referencing all those modules (and the root itself), for improved IDE experience?

Good proposal. I'll review it.

[darccio]

@RomainMuller It seems that the current opinion about go.work is that they represent local paths that aren't shareable. Check PR #1778 for more detail.

[darccio]

CI looks green and great:

[darccio]

As agreed, I'll merge this PR and next ones without CR as long as CI shows that the contribs' tests are running properly.