contrib: implement http.route in missing contribs

[rarguelloF]

What does this PR do?

Implement http.route tag in the following contribs:

• contrib/dimfeld/httptreemux.v5
• contrib/gofiber/fiber.v2
• contrib/emicklei/go-restful.v3
• contrib/zenazn/goji.v1/web

Also added some tests and smaller refactors in other contribs.

Motivation

Consistent implementation of http.route across languages and frameworks

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: 2023-10-23 09:15:26

Comparing candidate commit 6e282a2 in PR branch rarguelloF/http-route with baseline commit 00055c7 in branch main.

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