feat: Add Auto Lifecycle Toggle Feature

[itsSagarBro]

Description

This pull request introduces a new feature to the mobile_scanner Flutter plugin - Auto Lifecycle Toggle. The feature allows automatic toggling of the scanner's lifecycle based on the state of the Flutter widget, enhancing the plugin's usability and integration into various Flutter applications.

Changes Made

• Added a new feature: Auto Lifecycle Toggle
• Implemented logic for automatic toggling of the scanner's lifecycle
• Updated documentation to reflect the new feature

Usage

To enable the Auto Lifecycle Toggle feature, developers can set the corresponding parameter when initializing the scanner. This feature helps in seamlessly managing the scanner's lifecycle without manual intervention.

Example

MobileScanner(
  autoLifecycle: false,
  onDetect: (barcodes) {},
)

Testing

Describe the testing process you followed to ensure the reliability and correctness of the new feature.

Checklist

✅ Added tests
✅ Followed the code style guidelines
✅ Checked compatibility with the latest Flutter version

[navaronbracke]

@itsSagarBro This won't be needed, as we will remove the lifecycle handling (start/stop) from the MobileScanner widget in the next major release. I do agree that the current implementation causes issues (i.e. during reparenting in the widget tree).