feat: http client integration

[aldy505]

An effort to implement this: https://develop.sentry.dev/sdk/telemetry/traces/modules/requests/

Since we already have tracing without performance, this should be good to go.

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 86.23%. Comparing base (c243873) to head (4cc9a92).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #876      +/-   ##
==========================================
+ Coverage   86.07%   86.23%   +0.16%     
==========================================
  Files          62       63       +1     
  Lines        6090     6148      +58     
==========================================
+ Hits         5242     5302      +60     
+ Misses        634      631       -3     
- Partials      214      215       +1     

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[ribice]

@aldy505 We should document this (in _examples, and perhaps sentry-docs?), and also update changelog accordingly.

[aldy505]

Some golint errors, I'll fix that later

[aldy505]

@giortzisg @cleptric Is there anything that's blocking this PR to be merged?

[cleptric]

Not sure we actually want to go the route with the round tripper. But we take another look after logs.

[aldy505]

@cleptric @giortzisg any updates?

[giortzisg]

Will have a look after transport refactoring.

[aldy505]

@giortzisg updated