job: make charging constraint update criteria customizable

Make JobScheduler's charging constraint update criteria customizable to
adapt devices other than phone.

The criterias are:
  1. BATTERY_CHARGING_STATE_UPDATE_DELAY
  2. (newly added) BATTERY_CHARGING_STATE_ENFORCE_LEVEL

Their default values are init by SettingsProvider
and configured by res/values/default.xml as:
  - def_battery_charging_state_update_delay_ms
  - def_battery_charging_state_enforce_level

Other device now can override the default values by defining them in
device overlay default.xml.

Test: go/wear-charging-constraints-verification
BUG: 258718987
BUG: 308679533
Change-Id: I5d329db0ab67df203353f18a5afa5f9a182b5867