Add new background script handler to move arbitrary tabs

[jackmac92]

I wanted to add a custom shortcut to move all tabs, which meet X criteria, to the left side of the tab bar.
But I wasn't able to do so with the existing RUNTIME handlers, since they largely rely on moving the active tab.

Didn't spend much time on the API for this handler yet, open to suggestions if you have any

Currently it expects a Array of 2 item arrays [tabId, moveParams] *

api.RUNTIME("moveTabs", [
  [tabId1, { index: -1 }]
])

where moveParams is passed directly as the second arg to chrome.tabs.move for maximum flexibility

* pseudo "tuples", maybe this should be an object, just seemed slightly more confusing as an object with regard to what was passed as the second argument to chrome.tabs.move