all: Split Filesystem trait by Hierarchy/Copier and move errors into …

…associated types (#108)

The Filesystem trait encompasses both reading filesystem metadata (i.e.
hierarchy) and copying data into block devices. The former does not
depend on the latter, and does not even require knowing any information
about the block device type, which makes extending the filesystem to
multiple devices difficult.

This is evident in the old design in `copy_file_buf`, which is
essentially a filesystem copier into a `&mut [u8]`. Since Filesystem
must supply both hierarchy and copying functions, this had to be
separate.

In the new design, filesystems need only implement FilesystemHierarchy,
and can implement as many FilesystemCopiers as needed for individual
block device types.

This also overhauls error handling to use associated types, cleaning up
signatures, and error enums keep better track of where the error
occurred (e.g. in the hierarchy vs copier, or in the block device).

.github/workflows/check.yml

@@ -10,7 +10,7 @@ name: Check
 jobs:
   check:
     name: Check and lint
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04 # FIXME: 24.04 missing libwebkit2gtk-4, required for Tauri
     steps: 
       - name: Checkout source
         uses: actions/checkout@v3

.github/workflows/ci.yml

@@ -58,7 +58,7 @@ jobs:
         run: zip -j xdvdfs-linux-${{ github.sha }}.zip LICENSE target/release/xdvdfs
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: xdvdfs-linux-${{ github.sha }}
           path: xdvdfs-linux-${{ github.sha }}.zip
@@ -89,7 +89,7 @@ jobs:
         run: zip -j xdvdfs-windows-${{ github.sha }}.zip LICENSE target/x86_64-pc-windows-gnu/release/xdvdfs.exe
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: xdvdfs-windows-${{ github.sha }}
           path: xdvdfs-windows-${{ github.sha }}.zip
@@ -123,7 +123,7 @@ jobs:
         working-directory: ./xdvdfs-web
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: xdvdfs-web-${{ github.sha }}
           path: xdvdfs-web/xdvdfs-web-${{ github.sha }}.zip
@@ -162,7 +162,7 @@ jobs:
           projectPath: ./xdvdfs-desktop
 
       - name: Upload Artifacts
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: xdvdfs-desktop-${{ matrix.platform }}-${{ github.sha }}
           path: |