Stats: Transition HIDL clients to the new AIDL APIs

Transition performed for below vendor atoms:
- VENDOR_BATTERY_HEALTH_SNAPSHOT
- VENDOR_BATTERY_CAUSED_SHUTDOWN
Added StatsHelper class to remove code duplication
Removed HIDL Stats service usage

Eldar: https://eldar.corp.google.com/assessments/22665602/drafts/757729966
Bug: 181351177
Test: build, flash & boot
Test: adb shell cmd stats print-stats for all new atoms IDs
Change-Id: Id651ffd983380113dbf6a9c0c6adb74f861eb217
7 files changed