feat(net/http/otelhttp): Add http.route attribute

[gaiaz-iusipov]

In this pull request, I add recording of the http.route metric attribute for net/http/otelhttp.

The routeFromRequest function code is duplicated, and it might be better to move it to semconv.HTTPServer.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.2%. Comparing base (0a5b338) to head (1f60395).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #8632   +/-   ##
=====================================
  Coverage   82.1%   82.2%           
=====================================
  Files        183     183           
  Lines      13798   13810   +12     
=====================================
+ Hits       11340   11352   +12     
  Misses      2054    2054           
  Partials     404     404           

Files with missing lines	Coverage Δ
.../go-restful/otelrestful/internal/semconv/server.go	83.2% <100.0%> (+0.1%)	⬆️
...m/gin-gonic/gin/otelgin/internal/semconv/server.go	83.2% <100.0%> (+0.1%)	⬆️
...com/gorilla/mux/otelmux/internal/semconv/server.go	83.2% <100.0%> (+0.1%)	⬆️
.../labstack/echo/otelecho/internal/semconv/server.go	83.2% <100.0%> (+0.1%)	⬆️
...httptrace/otelhttptrace/internal/semconv/server.go	83.2% <100.0%> (+0.1%)	⬆️
...ation/net/http/otelhttp/internal/semconv/server.go	83.2% <100.0%> (+0.1%)	⬆️

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[pellared]

Can you please create an issue first?

From https://github.com/open-telemetry/opentelemetry-go-contrib/blob/main/CONTRIBUTING.md#contributing-code:

It's recommended that you signal your intention to contribute in the issue tracker, either by filing a new issue or by claiming an existing one.

[dmathieu]

Could this be done with a Labeler?

[gaiaz-iusipov]

I created an issue where I tried to explain my motivation: #8633

[gaiaz-iusipov]

I changed the logic so that the attribute is recorded by default, with an option to disable it. There is also still the question of moving the routeFromRequest function to the semconv package. Let’s discuss the final approach in the issue.

[gaiaz-iusipov]

Could this be done with a Labeler?

Sure it could, but @pellared pointed out in the issue that this attribute should always (when it is available) be recorded by default.

[dmathieu]

Sure, though this is not what that PR was doing when I left my comment.
Now: the attribute can be removed with a view. Why do we need the option?

[gaiaz-iusipov]

Sure, though this is not what that PR was doing when I left my comment. Now: the attribute can be removed with a view. Why do we need the option?

So it turns out the option is not needed at all. What about moving the routeFromRequest function to semconv.HTTPServer and making it public since its logic is duplicated?

[flc1125]

Some small adjustments.

[gaiaz-iusipov]

I think this PR is ready to merge.

[dmathieu]

I'm waiting for @pellared's review, since he requested changes.