Add updateDateTaken method to modify asset creation time on iOS, macOS, and Android

[Copilot]

Implements the ability to modify the creation date metadata of photos and videos after they've been saved to the gallery.

Changes

Dart API

• Added updateDateTaken(entity, dateTime) to DarwinEditor and AndroidEditor
• Returns updated AssetEntity with new createDateSecond or throws StateError on failure

iOS/macOS (darwin/)

• Implemented via PHAssetChangeRequest.creationDate property
• Uses performChangesAndWait with proper validation of edit permissions

Android (android/)

• Updates MediaStore.MediaColumns.DATE_TAKEN field
• Requires API 29+; returns false on older versions
• Timestamp converted from seconds to milliseconds for MediaStore

Usage

// Platform-specific
final newDate = DateTime(2023, 1, 15, 10, 30);
final updatedAsset = await PhotoManager().editor.darwin.updateDateTaken(
  entity: asset,
  dateTime: newDate,
);

// Or for Android
final updatedAsset = await PhotoManager().editor.android.updateDateTaken(
  entity: asset,
  dateTime: newDate,
);

Platform Support

• iOS 8+ / macOS 10.11+: ✅
• Android Q+ (API 29+): ✅
• Android P- (API 28-): ❌ (returns false)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Feature request] Support modifying the creation time of pictures or videos</issue_title>
<issue_description>### Platforms

iOS, macOS

Description

Can iOS and macOS support modifying the creation time of pictures or videos?

Why

No response

Additional

Better support modifications on Android, too.</issue_description>

Comments on the Issue (you are @copilot in this section)

@CaiJingLong Looking at the [documentation][doc] , it should be possible.

• Fixes [Feature request] Support modifying the creation time of pictures or videos #992

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