Clean up and updates to dependencies and modification of the Flutterwave.charge() charge

[Dekunledev]

• Modified Flutterwave.charge() method to accept a BuildContext parameter.
• Added context.mounted checks to prevent setState calls after widget disposal.
• Enhanced success status check logic to handle different status values ("success" and "completed").
• Improved error handling and state management.
• Removed deprecated components: flutterwave_style.dart and standard_webview.dart.
• Updated SDK requirements to >=2.17.0.
• Upgraded dependencies to latest versions.
• Removed unused dependencies: webview_flutter, modal_bottom_sheet and uuid.