Added Dockerfile for build environment

Dockerfile

@@ -0,0 +1,38 @@
+#
+# To Build:
+#       docker build -t usbvalve/arduino-cli .
+#
+# To Run:
+#       docker run --rm --name usbvalve -v $PWD:/mnt usbvalve/arduino-cli /mnt/USBvalve
+#
+
+FROM ubuntu:22.04
+WORKDIR /app
+
+# OS setup
+RUN apt-get update -y \ 
+    && apt-get install -y git wget python3 \
+    && apt-get autoremove -y \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
+
+# arduino-cli setup
+RUN cd /app \
+    && git clone --recursive https://github.com/arduino/arduino-cli.git \
+    && cd arduino-cli \
+    && ./install.sh \
+    && export PATH=$PATH:/app/arduino-cli/bin \
+    && arduino-cli  --additional-urls https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json core search 2040 \
+    && arduino-cli --additional-urls https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json core install rp2040:rp2040 \
+    && arduino-cli lib install "Adafruit TinyUSB Library" \
+    && arduino-cli lib install "ssd1306" \
+    && arduino-cli lib install "Pico PIO USB" \
+    && arduino-cli lib install "SSD1306Ascii"
+
+# Compilation setup
+RUN echo  "#!/bin/bash" > /app/entrypoint.sh \
+    && echo  "export PATH=\$PATH:/app/arduino-cli/bin" >> /app/entrypoint.sh \
+    && echo  "arduino-cli compile --fqbn rp2040:rp2040:rpipico --board-options \"usbstack=tinyusb\" --board-options \"freq=240\" --output-dir \"/mnt/USBvalve_out\" \"\$1\"" >> /app/entrypoint.sh \
+    && chmod +x /app/entrypoint.sh
+
+ENTRYPOINT ["/app/entrypoint.sh"]