Rename plugin directories to have chrome. prefix

Also update plugin IDs to start with org.chromium
Move xhr-blob and CustomEvent plugins into plugins/
Move Function.bind polyfill into its own plugin
Fix up require paths to match updated plugin IDs (oops).
Removing samples dir
adding alarms
Updating alarms.
Adding warnings to alarms tests about flakiness caused by scrolling the display during a test.
Renaming alarms directory to chrome.alarms.
Changing id of alarms plugin to org.chromium.chrome.alarms.