Expose TLS handshake timing to response

[antekresic]

No related issue, missed this in the previous PR #446.

[codecov-io]

Codecov Report

Merging #454 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #454      +/-   ##
==========================================
+ Coverage   62.89%   62.89%   +<.01%     
==========================================
  Files          90       90              
  Lines        6376     6377       +1     
==========================================
+ Hits         4010     4011       +1     
  Misses       2145     2145              
  Partials      221      221

Impacted Files	Coverage Δ
js/modules/k6/http/response.go	65.25% <ø> (ø)	⬆️
js/modules/k6/http/http_request.go	88.29% <100%> (+0.04%)	⬆️

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[robingustafsson]

Thanks @antekresic! LGTM, merging.