Don't silently hit a URL for raw client cookie support

[LegNeato]

It is unexpected that using the raw client loads a completely different URL first to get cookies:

fantoccini/src/client.rs

Line 751 in 6a7203e

self.goto(cookie_url.as_str()).await?;

We should probably create typestates and specific functions to drive them and not do this automatically. Or perhaps let the URL be configured.

[jonhoo]

Yeah, it's really awkward, but as best as I can tell from the WebDriver standard, it's the only way to get cookies for a given domain. This is tracked for the spec in w3c/webdriver#1238.

[LegNeato]

My problem is the silent request is tripping bot detection, as this request + the "real" request happen too close together and the site sees me as a bot.

I'd like to at least be able to customize the url that is hit or skip this if I know I already have the cookies I want...would you take a PR to add that?

[jonhoo]

Yeah, a PR seems like a good idea!