health: Convert of health HAL to AIDL

On top of the hidl2aidl translation, the following is
done manually:

- Renamed the package from health2 to health. Also pulls in
health@1.0::Battery* enums.
- Removes Result and Constants enum. Result values are returned
as transaction status codes.
- Removes health@2.1 charger related APIs.
  - remove shouldKeepScreenOn
  - remove getHealthConfig
  - remove HealthConfig type
- Removes StorageAttribute because it is not used in the framework
- Add units to HealthInfo fields and IHealth methods.
- Update docs (namely, u -> µ in various places)

Bug: 177269435
Test: pass

Change-Id: I9c9a9d9dd5d49142258e608a463412d3e89e91a3