Update Containerfile to make it Docker compatible

- Replace COPY command with Docker compatible syntax
- Rename container tag to bambu-studio-builder so as to not confuse with a container that would actually run Bambu Studio
- Add Docker alternative build method (thx @sg-r)
- Update podman syntax to remove unnecessary sudo

Containerfile

@@ -1,16 +1,22 @@
 # Build Bambu Slicer in a container
 #
-# Build an AppImage:
-# rm -rf build; sudo podman build . -t bambu-studio  &&  sudo podman run --rm localhost/bambu-studio /bin/bash -c 'tar -c $(find build | grep ubu64.AppImage | head -1)' | tar -xv
+# Build an AppImage using rootless Podman (refer to https://github.com/containers/podman/blob/main/docs/tutorials/rootless_tutorial.md):
+# rm -rf build; podman build . -t bambu-studio-builder && podman run --rm localhost/bambu-studio-builder /bin/bash -c 'tar -c $(find build | grep ubu64.AppImage | head -1)' | tar -xv
 #
 # Troubleshooting the build container:
-# sudo podman run -it --name bambu-studio localhost/bambu-studio /bin/bash
+# podman run -it --name bambu-studio-builder localhost/bambu-studio-builder /bin/bash
 #
 # Debugging the resulting AppImage:
 #   1) Install `gdb`
 #   2) In a terminal in the same directory as the AppImage, start it with following:
 #      echo -e "run\nbt\nquit" | gdb ./BambuStudio_ubu64.AppImage
 #   3) Find related issue using backtrace output for clues and add backtrace to it on github
+#
+# Docker alternative AppImage build syntax (use this if you can't install podman):
+# rm -rf build; docker build . --file Containerfile -t bambu-studio-builder; docker run --rm bambu-studio-builder /bin/bash -c 'tar -c $(find build | grep ubu64.AppImage | head -1)' | tar -xv
+#
+#
+# TODO: bind mount BambuStudio to inside the container instead of COPY to enable faster rebuilds during dev work.
 
 FROM docker.io/ubuntu:20.04
 LABEL maintainer "DeftDawg <[email protected]>"
@@ -46,7 +52,7 @@ RUN apt-get update && apt-get install  -y \
     file \
     sudo
 
-COPY ../BambuStudio BambuStudio
+COPY ./ BambuStudio
 
 WORKDIR BambuStudio