easy-signin: Show tooltip for first login after setup.
- Migrate hardlock state from user prefs to local state;
- Change hardlock state from a boolean to an enum to support multiple hardlock
cases;
- PAIRING_CHANGED hardlock when user has pairing data but it is different from
cryptohome keys;
- NO_PAIRING when user has no pairing data;
- Refresh easy unlock keys when lock screen is dismissed
with password;
Unrelated fix:
- Move prefs::kEasyUnlockAllowed to EasyUnlockServiceRegular because it is
a user pref/policy;
BUG=419099
Review URL: https://codereview.chromium.org/
619443003
Cr-Commit-Position: refs/heads/master@{#298245}