[ChromeDriver] W3C compliant parsing proxy setting

Update parsing of proxy settings in session capabilities, for W3C
compliance. Changes include:
* Handle noProxy containing a list of strings.
* Handle socksProxy and socksVersion.
* Return kInvalidArgument for errors.

Bug: chromedriver:2537
Change-Id: I545291b8249e147f75babee5dfe72137bfc4cdca
Reviewed-on: https://chromium-review.googlesource.com/1226096
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#591496}
2 files changed