Add ability to get current "User-Agent" for browser session. Related to #639

[rosolko]

Proposed changes

Add "User-Agent" header when downloading file. Related to #639

Checklist

• Checkstyle and unit tests pass locally with my changes by running gradle check chrome htmlunit command
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[coveralls]

Coverage increased (+0.03%) to 64.34% when pulling ee488d3 on rosolko:user_agent into 5a8d489 on codeborne:master.

[codecov-io]

Codecov Report

Merging #657 into master will increase coverage by 0.1%.
The diff coverage is 50%.

@@             Coverage Diff             @@
##             master     #657     +/-   ##
===========================================
+ Coverage     60.49%   60.59%   +0.1%     
- Complexity      771      772      +1     
===========================================
  Files           148      148             
  Lines          2749     2751      +2     
  Branches        270      270             
===========================================
+ Hits           1663     1667      +4     
+ Misses          981      980      -1     
+ Partials        105      104      -1

Impacted Files	Coverage Δ	Complexity Δ
src/main/java/com/codeborne/selenide/Selenide.java	0% <0%> (ø)	0 <0> (ø)	⬇️
...rne/selenide/impl/DownloadFileWithHttpRequest.java	79.72% <100%> (+0.27%)	15 <0> (ø)	⬇️
...e/selenide/impl/WebDriverThreadLocalContainer.java	82.6% <0%> (+2.17%)	31% <0%> (+1%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5a8d489...607eef0. Read the comment docs.

[coveralls]

Coverage increased (+0.06%) to 64.377% when pulling 607eef0 on rosolko:user_agent into 5a8d489 on codeborne:master.

[rosolko]

I don't know why reason, but codecov/patch won't pass :(

[BorisOsipov]

@rosolko relax and don't care :)

[BorisOsipov]

Thanks @rosolko
Merged b9a8840