Battery not low constraint

[dombroks]

This pull request adds support for a new "require battery not low" constraint throughout the Lorraine job scheduling library, including both data model and platform-specific implementations. The main changes include updating the constraints data structures, database schema, and adding iOS-specific logic for checking battery state.

Constraint Model and Entity Updates:

• Added a new requireBatteryNotLow property to LorraineConstraints, ConstraintEntity, and their conversion functions, allowing jobs to specify this constraint. [1] [2]
• Updated the builder API (LorraineConstraintsDefinition) to support the new constraint.

Database Schema Migration:

• Increased database version to 3 and updated the schema to store the new require_battery_not_low field in the worker table. [1] [2]

Android and iOS Platform Integration:

• Modified the Android mapping (asWorkManagerConstraints) to set requiresBatteryNotLow based on the new property.
• Registered a new BatteryNotLowCheck constraint check on iOS, integrating it into the platform's constraint checks. [1] [2]

iOS Battery Constraint Implementation:

• Introduced BatteryNotLowCheck and AppleBatteryObserver classes to monitor battery state and expose the "not low" status to the scheduler, using UIKit battery notifications.