Rename and move some properties to where they belong

[vringar]

browser_pid -> geckodriver_pid as this is no longer the Firefox pid
Move visit_id to be a property of the command_sequence instead of the browser
Edit: Scoped this more narrowly as #701 is for the discussion of crawl, browser and task

[shreyagupta30]

Hello @vringar can I work on this?

[vringar]

Sure :)

[vringar]

Hey @shreyagupta30 are you still on this?
Otherwise I'd pick this up myself.

[shreyagupta30]

Hi @vringar, you can take this up. Sorry!

[birdsarah]

@vringar can we scope down this issue to just:

• browser_pid -> geckodriver_pid as this is no longer the Firefox pid
• Move visit_id to be a property of the command_sequence instead of the browser

And have #701 for the task / crawl / browser?

[vringar]

Moving visit_id into the command_sequence is more work than expected, since we never pass the CommandSequence to the BrowserManager only singular commands over the command_queue