Fix flatpak build (#7283)

* Patch wxWidgets to automatically select dark theme variant (taken from
  Bambu slicer flatpak manifest)
* Drop python script that selected dark theme
* Add a patch to fix libslic3r build

.github/workflows/build_all.yml

@@ -60,21 +60,21 @@ jobs:
       arch: ${{ matrix.arch }}
       build-deps-only: ${{ inputs.build-deps-only || false }}
     secrets: inherit
-  # flatpak:
-  #   name: "Flatpak"
-  #   runs-on: ubuntu-latest
-  #   container:
-  #     image: bilelmoussaoui/flatpak-github-actions:gnome-45
-  #     options: --privileged
-  #   steps:
-  #   # maybe i'm too dumb and fucked up to do CI. OH WELL :D -ppd
-  #   - name: "Remove unneeded stuff to free disk space"
-  #     run:
-  #       sudo rm -rf /usr/share/dotnet /opt/ghc "/usr/local/share/boost" "$AGENT_TOOLSDIRECTORY"
-  #   - uses: actions/checkout@v4
-  #   - uses: flatpak/flatpak-github-actions/flatpak-builder@v6
-  #     with:
-  #       bundle: orcaslicer.flatpak
-  #       manifest-path: flatpak/io.github.softfever.OrcaSlicer.yml
-  #       cache-key: flatpak-builder-${{ github.sha }}
-  #       cache: false
+  flatpak:
+    name: "Flatpak"
+    runs-on: ubuntu-latest
+    container:
+      image: bilelmoussaoui/flatpak-github-actions:gnome-46
+      options: --privileged
+    steps:
+    # maybe i'm too dumb and fucked up to do CI. OH WELL :D -ppd
+    - name: "Remove unneeded stuff to free disk space"
+      run:
+        sudo rm -rf /usr/share/dotnet /opt/ghc "/usr/local/share/boost" "$AGENT_TOOLSDIRECTORY"
+    - uses: actions/checkout@v4
+    - uses: flatpak/flatpak-github-actions/flatpak-builder@v6
+      with:
+        bundle: orcaslicer.flatpak
+        manifest-path: flatpak/io.github.softfever.OrcaSlicer.yml
+        cache-key: flatpak-builder-${{ github.sha }}
+        cache: false