healthd: partially fill in health 2.1 HAL fields

- batteryCurrentAverage
- batteryCapacityLevel
- batteryChargeTimeToFullNowSeconds
- batteryFullCapacityUah

Some of the fields are left 0 / UNKNOWN and will be
implemented in b/142260281.

Bug: 142260281

Test: lshal debug health 2.1 HAL shows these values
Change-Id: I8e462d612b39c16cfb3ae1b63b3e293153585c28