Add hostname as parameter for GoogleChrome/lighthouse#2727

[salvocanna]

Convert the parameter configs to object to make it more extensible and add the hostname parameter.
This is actually in conflict with #2728
Whichever makes more sense, as long as we can have a host param :)

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[salvocanna]

CLA: I signed it!

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CLAs look good, thanks!

[paulirish]

Did you confirm this works? I thought I recall remote-debugging-port only listening to localhost by default. 😕

[brendankenny]

Closing in favor of #2728

@salvocanna please weigh in on that PR so we can make sure it meets everyone's needs 👍🎉