feature(mobile): hash assets & sync via checksum (#2592)

* compare different sha1 implementations

* remove openssl sha1

* sync via checksum

* hash assets in batches

* hash in background, show spinner in tab

* undo tmp changes

* migrate by clearing assets

* ignore duplicate assets

* error handling

* trigger sync/merge after download and update view

* review feedback improvements

* hash in background isolate on iOS

* rework linking assets with existing from DB

* fine-grained errors on unique index violation

* hash lenth validation

* revert compute in background on iOS

* ignore duplicate assets on device

* fix bug with batching based on accumulated size

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Co-authored-by: Fynn Petersen-Frey <zoodyy@users.noreply.github.com>

mobile/lib/modules/asset_viewer/views/gallery_viewer.dart

@@ -287,7 +287,7 @@ class GalleryViewerPage extends HookConsumerWidget {
             isFavorite: asset().isFavorite,
             onMoreInfoPressed: showInfo,
             onFavorite: asset().isRemote ? () => toggleFavorite(asset()) : null,
-            onDownloadPressed: asset().storage == AssetState.local
+            onDownloadPressed: asset().isLocal
                 ? null
                 : () =>
                     ref.watch(imageViewerStateProvider.notifier).downloadAsset(